WO2015186749A1

WO2015186749A1 - Method for producing l-amino acids

Info

Publication number: WO2015186749A1
Application number: PCT/JP2015/066072
Authority: WO
Inventors: 秀高土井; 晶子松平; 臼田　佳弘
Original assignee: 味の素株式会社
Priority date: 2014-06-03
Filing date: 2015-06-03
Publication date: 2015-12-10
Also published as: JP2017131111A; EP3153586A1; EP3153586A4; EP3153586B1; US20170073714A1; US10563234B2; BR112016028185A2

Abstract

Provided is a method for producing L-amino acids. L-amino acids are produced by subjecting bacteria belonging to the family Enterobacteriaceae, which have the ability to produce L-amino acids and have been modified such that aconitase activity is increased or aconitase activity and acetaldehyde dehydrogenase activity are increased, to culture in an ethanol-containing culture medium, and collecting the L-amino acids from the culture medium or the bacterial cells.

Description

Method for producing L-amino acid

The present invention relates to a method for producing L-amino acids using bacteria. L-amino acids are industrially useful as additives for animal feed, ingredients for seasonings and foods and drinks, amino acid infusions, and the like.

L-amino acids are industrially produced, for example, by fermentation using various microorganisms capable of producing L-amino acids. Examples of methods for producing L-amino acids by fermentation include a method using a wild-type microorganism (wild strain), a method using an auxotrophic strain derived from a wild strain, and various drug-resistant mutant strains derived from a wild strain. And a method using a strain having characteristics of both an auxotrophic strain and a metabolic control mutant.

In recent years, microorganisms whose L-amino acid producing ability has been improved by recombinant DNA technology have been used for the production of L-amino acids. Examples of a method for improving the L-amino acid producing ability of a microorganism include, for example, enhancing the expression of a gene encoding an L-amino acid biosynthetic enzyme (Patent Documents 1 and 2) or an L-amino acid biosynthetic system. To enhance the inflow of the carbon source (Patent Document 3).

Conventionally, in the industrial production of target substances such as L-amino acids by fermentation, glucose, fructose, sucrose, waste molasses, starch hydrolysates and the like have been used as carbon sources.

On the other hand, alcohols such as ethanol can be used as a carbon source. As a method for producing L-amino acid by fermentation using ethanol as a carbon source, for example, a method utilizing a bacterium of the family Enterobacteriaceae modified so as to express alcohol dehydrogenase under aerobic conditions (Patent Document 4), A method using a bacterium from the family Enterobacteriaceae modified so as to increase the activity of pyruvate synthase or pyruvate: NADP ⁺ oxidoreductase (Patent Document 5), and an intestine modified so as to decrease the activity of ribonuclease G A method using an endobacterium (Patent Document 6), a method using an enterobacteriaceae bacteria modified to have a mutant ribosome S1 protein (Patent Document 7), and the activity of the AldB protein decreases. Using the bacteria of the family Enterobacteriaceae so modified (Patent Document 8), the intestines modified so that the intracellular hydrogen peroxide concentration is lowered Methods utilizing bacteria family bacteria (Patent Document 9) are known.

Aconitase is a dehydratase / hydratase (EC 4.2.1.3) that reversibly catalyzes the isomerization reaction between citric acid and isocitrate in the TCA cycle and the glyoxylate cycle. Escherichia coli has at least two aconitase isozymes, AcnA and AcnB. The amino acid sequence identity between AcnA and AcnB is about 17%. AcnB is a major aconitase in Escherichia coli, and is expressed particularly in the logarithmic growth phase (Non-patent Document 1). On the other hand, AcnA is induced by iron or oxidative stress, and is expressed particularly in the stationary phase (Non-patent Document 1).

Acetaldehyde dehydrogenase is an enzyme (EC 1.2.1.3, EC 1.2.1.4, EC 1.2.1.5, EC) that reversibly catalyzes the reaction of producing acetic acid from acetaldehyde using NAD ⁺ or NADP ⁺ as an electron acceptor. 1.2.1.22 etc.). For example, the Escherichia coli AldB protein has acetaldehyde dehydrogenase activity using NADP ⁺ as an electron acceptor. As described above, it is known that a decrease in the activity of AldB protein is effective for the production of L-amino acids using ethanol as a carbon source.

U.S. Pat.No. 5,168,056 U.S. Pat.No. 5,776,736 U.S. Pat.No. 5,906,925 WO2008 / 010565 WO2009 / 031565 WO2010 / 101053 WO2011 / 096554 WO2012 / 002486 JP2014-036576

An object of the present invention is to develop a novel technique for improving L-amino acid-producing ability of bacteria and to provide an efficient method for producing L-amino acid.

As a result of intensive research to solve the above-mentioned problems, the present inventor has made ethanol carbon by modifying bacteria so that aconitase activity is increased or aconitase activity and acetaldehyde dehydrogenase activity are increased. The present inventors have found that L-amino acid production by the same bacterium can be improved when used as a source.

That is, the present invention can be exemplified as follows.
[1]
Bacteria belonging to the family Enterobacteriaceae having L-amino acid producing ability are cultured in a medium containing ethanol, and L-amino acid is produced and accumulated in the medium or in the microbial cells, and from the medium or the microbial cells Collecting the L-amino acid, comprising the steps of:
The bacterium is modified to increase aconitase activity,
The method wherein the aconitase is an AcnB protein.
[2]
The aforementioned method, wherein the AcnB protein is a protein described in the following (a), (b), or (c):
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36;
(B) In the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36, the amino acid sequence includes substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and has an aconitase activity. protein;
(C) a protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36 and having aconitase activity.
[3]
Bacteria belonging to the family Enterobacteriaceae having L-amino acid producing ability are cultured in a medium containing ethanol, and L-amino acid is produced and accumulated in the medium or in the microbial cells, and from the medium or the microbial cells Collecting the L-amino acid, comprising the steps of:
A method wherein the bacterium has been modified to increase aconitase activity and acetaldehyde dehydrogenase activity.
[4]
The method, wherein the aconitase is an AcnA protein or an AcnB protein.
[5]
The method, wherein the AcnA protein is a protein described in (a), (b), or (c) below:
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 22, 24, 26, or 28;
(B) In the amino acid sequence shown in SEQ ID NO: 22, 24, 26, or 28, includes an amino acid sequence including substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and has an aconitase activity. protein;
(C) a protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 22, 24, 26, or 28 and having aconitase activity.
[6]
The aforementioned method, wherein the AcnB protein is a protein described in the following (a), (b), or (c):
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36;
(B) In the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36, the amino acid sequence includes substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and has an aconitase activity. protein;
(C) a protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36 and having aconitase activity.
[7]
The method, wherein the acetaldehyde dehydrogenase is an AldB protein.
[8]
The method, wherein the AldB protein is a protein described in the following (a), (b), or (c):
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 38, 40, 42, or 44;
(B) the amino acid sequence shown in SEQ ID NO: 38, 40, 42, or 44, comprising an amino acid sequence comprising substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and having acetaldehyde dehydrogenase activity A protein having;
(C) A protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 38, 40, 42, or 44 and having acetaldehyde dehydrogenase activity.
[9]
The method, wherein the bacterium is further modified to increase the activity of an ethanol metabolizing enzyme.
[10]
The method, wherein the bacterium can assimilate ethanol aerobically.
[11]
The bacterium has been modified to retain a mutant adhE gene;
The method, wherein the mutant adhE gene is an adhE gene encoding a mutant AdhE protein having a mutation that improves resistance to inactivation under aerobic conditions.
[12]
The mutation is a mutation in which the amino acid residue corresponding to the glutamic acid residue at position 568 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with an amino acid residue other than glutamic acid and aspartic acid in the amino acid sequence of the wild-type AdhE protein. Said method.
[13]
The method as described above, wherein the amino acid residue after substitution is a lysine residue.
[14]
The method, wherein the mutant AdhE protein further has the following additional mutation: :
(A) A mutation in which the amino acid residue corresponding to the glutamic acid residue at position 560 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with another amino acid residue in the amino acid sequence of the wild-type AdhE protein;
(B) a mutation in which the amino acid residue corresponding to the phenylalanine residue at position 566 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with another amino acid residue in the amino acid sequence of the wild-type AdhE protein;
(C) In the amino acid sequence of the wild-type AdhE protein, the glutamic acid residue at position 22, the methionine residue at position 236, the tyrosine residue at position 461, the isoleucine residue at position 554, and 786 in the amino acid sequence shown in SEQ ID NO: 46 A mutation in which the amino acid residue corresponding to the alanine residue at the position is substituted with another amino acid residue;
(D) Combination of the above mutations.
[15]
The method, wherein the bacterium is an Escherichia bacterium.
[16]
The method, wherein the bacterium is Escherichia coli.
[17]
The method, wherein the L-amino acid is L-lysine.
[18]
The method, wherein the bacterium further has the following properties:
(A) Dihydrodipicolinate reductase, diaminopimelate decarboxylase, diaminopimelate dehydrogenase, phosphoenolpyruvate carboxylase, aspartate aminotransferase, diaminopimelate epimerase, aspartate semialdehyde dehydrogenase, tetrahydrodipicolinate succinylase, and succinyl diaminopimelate deacylase Modified to increase the activity of one or more enzymes selected from
(B) modified to reduce the activity of lysine decarboxylase;
(C) A combination of the above properties.

The figure which shows the alignment of the amino acid sequence of various AldB protein. The figure which shows the alignment of the amino acid sequence of various AldB protein (continuation). The figure which shows the alignment of the amino acid sequence of various AdhE protein. The figure which shows the alignment of the amino acid sequence of various AdhE protein (continuation). The figure which shows the alignment of the amino acid sequence of various AdhE protein (continuation).

Hereinafter, the present invention will be described in detail.

The method of the present invention comprises culturing a bacterium belonging to the family Enterobacteriaceae having an L-amino acid-producing ability in a medium containing ethanol, and producing and accumulating L-amino acid in the medium or in the microbial cells, and A method for producing an L-amino acid comprising collecting an L-amino acid from the medium or microbial cells so that the bacterium has increased aconitase activity or increased aconitase activity and acetaldehyde dehydrogenase activity. The method is characterized in that the method is modified. The bacterium used in this method is also referred to as “the bacterium of the present invention”.

<1> Bacterium of the Present Invention The bacterium of the present invention is a bacterium belonging to the family Enterobacteriaceae having L-amino acid-producing ability, and has aconitase activity increased or aconitase activity and acetaldehyde dehydrogenase activity. Bacteria modified to increase.

<1-1> Bacteria having L-amino acid-producing ability In the present invention, “bacteria having L-amino acid-producing ability” refers to the extent that a desired L-amino acid can be produced and recovered when cultured in a medium. Refers to bacteria having the ability to accumulate in the medium or in the fungus body. The bacterium having L-amino acid-producing ability may be a bacterium capable of accumulating a larger amount of the target L-amino acid in the medium than the unmodified strain. Non-modified strains include wild strains and parent strains. The bacterium having L-amino acid-producing ability is a bacterium that can accumulate the target L-amino acid in an amount of 0.5 g / L or more, more preferably 1.0 g / L or more in the medium. May be.

L-amino acids include basic amino acids such as L-lysine, L-ornithine, L-arginine, L-histidine, L-citrulline, L-isoleucine, L-alanine, L-valine, L-leucine, glycine, etc. Aliphatic amino acids, amino acids which are hydroxymonoaminocarboxylic acids such as L-threonine and L-serine, cyclic amino acids such as L-proline, aromatic amino acids such as L-phenylalanine, L-tyrosine and L-tryptophan, L- Examples thereof include sulfur-containing amino acids such as cysteine, L-cystine and L-methionine, acidic amino acids such as L-glutamic acid and L-aspartic acid, and amino acids having an amide group in the side chain such as L-glutamine and L-asparagine. The bacterium of the present invention may have only one L-amino acid producing ability or may have two or more L-amino acid producing ability.

In the present invention, unless otherwise specified, any amino acid may be an L-amino acid. Further, the produced L-amino acid may be a free form, a salt thereof, or a mixture thereof. That is, in the present invention, the term “L-amino acid” may mean a free L-amino acid, a salt thereof, or a mixture thereof, unless otherwise specified. Examples of the salt will be described later.

The bacteria belonging to the family Enterobacteriaceae include Escherichia, Enterobacter, Pantoea, Klebsiella, Serratia, Erwinia, Photolabdas Examples include bacteria belonging to genera such as (Photorhabdus), Providencia, Salmonella, Morganella, and the like. Specifically, according to the taxonomy used in the NCBI (National Center for Biotechnology Information) database (http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=91347) Bacteria classified in the family Enterobacteriaceae can be used.

The Escherichia bacterium is not particularly limited, but includes bacteria classified into the genus Escherichia by classification known to microbiologists. Examples of Escherichia bacteria include, for example, Neidhardt et al. (Backmann, B. J. 1996. Derivations and Genotypes of some mutant derivatives of Escherichia coli K-12, p. 2460-2488. Table 1. In F. D. Nehard (ed.), “Escherichia, coli, and Salmonella, Cellular, and Molecular, Biology / Second Edition, American, Society, for Microbiology, Press, Washington, DC). Examples of bacteria belonging to the genus Escherichia include Escherichia coli. Specific examples of Escherichia coli include Escherichia coli W3110 (ATCC11027325) and Escherichia coli MG1655 (ATCC 47076) derived from the prototype wild-type strain K12.

The bacteria belonging to the genus Enterobacter are not particularly limited, but include bacteria classified into the genus Enterobacter by classification known to microbiologists. Examples of Enterobacter bacteria include Enterobacter agglomerans and Enterobacter aerogenes. Specific examples of Enterobacter agglomerans include the Enterobacter agglomerans ATCC12287 strain. Specific examples of Enterobacter aerogenes include Enterobacter aerogenes ATCC13048, NBRC12010 (BiotechonolonBioeng.eng2007 Mar 27; 98 (2) 340-348), AJ110637 (FERM BP-10955) . Examples of Enterobacter bacteria include those described in European Patent Application Publication No. EP0952221. Some Enterobacter agglomerans are classified as Pantoea agglomerans.

The Pantoea bacterium is not particularly limited, and examples include bacteria classified into the Pantoea genus by classification known to microbiologists. Examples of the genus Pantoea include Pantoea 、 ananatis, Pantoea stewartii, Pantoea agglomerans, and Pantoea citrea. Specifically, for example, Pantoea Ananatis LMG20103 strain, AJ13355 strain (FERM 、 BP-6614), AJ13356 strain (FERM BP-6615), AJ13601 strain (FERM BP-7207), SC17 strain (FERM BP) -11091), and SC17 (0) strain (VKPM B-9246). Certain types of Enterobacter agglomerans were recently reclassified as Pantoea agglomerans, Pantoea ananatis, Pantoea stewartii, etc. based on 16S rRNA nucleotide sequence analysis (Int. J. Syst. Bacteriol) ., 43, 162-173 (1993)). In the present invention, the Pantoea bacterium also includes a bacterium reclassified as Pantoea in this way.

Examples of the genus Erwinia include Erwinia amylovora and Erwinia carotovora. Examples of Klebsiella bacteria include Klebsiella planticola.

These strains can be sold, for example, from the American Type Culture Collection (address 12301 Parklawn Drive, Rockville, Maryland 20852 P.O. Box 1549, Manassas, VA 20108, United States States of America). That is, a registration number corresponding to each strain is given, and it is possible to receive a sale using this registration number (see http://www.atcc.org/). The registration number corresponding to each strain is described in the catalog of American Type Culture Collection.

The bacterium of the present invention may inherently have L-amino acid-producing ability or may have been modified to have L-amino acid-producing ability. A bacterium having L-amino acid-producing ability can be obtained, for example, by imparting L-amino acid-producing ability to the bacterium as described above, or by enhancing the L-amino acid-producing ability of the bacterium as described above. .

L-amino acid-producing ability can be imparted or enhanced by a method conventionally used for breeding amino acid-producing bacteria such as coryneform bacteria or Escherichia bacteria (Amino Acid Fermentation, Academic Publishing Center, Inc., 1986). (May 30, 1st edition issued, see pages 77-100). Examples of such methods include acquisition of auxotrophic mutants, acquisition of L-amino acid analog-resistant strains, acquisition of metabolic control mutants, and recombination with enhanced activity of L-amino acid biosynthetic enzymes. The creation of stocks. In the breeding of L-amino acid-producing bacteria, properties such as auxotrophy, analog resistance, and metabolic control mutation that are imparted may be single, or two or more. In addition, L-amino acid biosynthetic enzymes whose activities are enhanced in breeding L-amino acid-producing bacteria may be used alone or in combination of two or more. Furthermore, imparting properties such as auxotrophy, analog resistance, and metabolic control mutation may be combined with enhancing the activity of biosynthetic enzymes.

An auxotrophic mutant, an analog resistant strain, or a metabolically controlled mutant having L-amino acid production ability is subjected to normal mutation treatment of the parent strain or wild strain, and the auxotrophic, analog It can be obtained by selecting those exhibiting resistance or metabolic control mutations and having the ability to produce L-amino acids. Normal mutation treatments include X-ray and ultraviolet irradiation, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), ethyl methane sulfonate (EMS), methyl methane sulfonate (MMS), etc. Treatment with a mutagen is included.

Also, the L-amino acid-producing ability can be imparted or enhanced by enhancing the activity of an enzyme involved in the target L-amino acid biosynthesis. Enhancing enzyme activity can be performed, for example, by modifying bacteria so that expression of a gene encoding the enzyme is enhanced. Methods for enhancing gene expression are described in WO00 / 18935 pamphlet, European Patent Application Publication No. 1010755, and the like. A detailed method for enhancing the enzyme activity will be described later.

Furthermore, the L-amino acid-producing ability can be imparted or enhanced by reducing the activity of an enzyme that catalyzes a reaction that branches from the biosynthetic pathway of the target L-amino acid to produce a compound other than the target L-amino acid. It can be carried out. As used herein, “an enzyme that catalyzes a reaction that produces a compound other than the target L-amino acid by branching from the biosynthetic pathway of the target L-amino acid” includes enzymes involved in the degradation of the target amino acid. It is. A method for reducing the enzyme activity will be described later.

Specific examples of L-amino acid-producing bacteria and methods for imparting or enhancing L-amino acid-producing ability are given below. In addition, any of the modifications exemplified below for imparting or enhancing the properties of L-amino acid-producing bacteria and L-amino acid-producing ability may be used alone or in appropriate combination.

<L-glutamic acid producing bacteria>
Examples of the method for imparting or enhancing L-glutamic acid-producing ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-glutamic acid biosynthetic enzymes is increased. . Such enzymes include, but are not limited to, glutamate dehydrogenase (gdhA), glutamine synthetase (glnA), glutamate synthase (gltBD), isocitrate dehydrogenase (icdA), aconite hydratase (acnA, acnB), citrate synthase (GltA), methyl citrate synthase (prpC), pyruvate carboxylase (pyc), pyruvate dehydrogenase (aceEF, lpdA), pyruvate kinase (pykA, pykF), phosphoenolpyruvate synthase (ppsA), enolase (eno) Phosphoglyceromutase (pgmA, pgmI), phosphoglycerate kinase (pgk), glyceraldehyde-3-phosphate dehydrogenase (gapA), triosephosphate isomerase (tpiA), fructose bisphosphate aldolase (fbp), glucose phosphate isomerase Ze (pgi), 6- phosphogluconate dehydratase (edd), 2-keto-3-deoxy-6-phosphogluconate aldolase (eda), include transhydrogenase. The parentheses are examples of genes encoding the enzymes (the same applies to the following description). Among these enzymes, it is preferable to enhance the activity of one or more enzymes selected from, for example, glutamate dehydrogenase, citrate synthase, phosphoenolpyruvate carboxylase, and methyl citrate synthase.

Strains belonging to the family Enterobacteriaceae that have been modified to increase expression of the citrate synthase gene, phosphoenolpyruvate carboxylase gene, and / or glutamate dehydrogenase gene include those disclosed in EP1078989A, EP955368A, and EP952221A Can be mentioned. Examples of strains belonging to the family Enterobacteriaceae that have been modified to increase the expression of the Entner-Doudoroff pathway genes (edd, eda) include those disclosed in EP1352966B.

The method for imparting or enhancing the ability to produce L-glutamic acid is, for example, selected from enzymes that catalyze a reaction that branches from the biosynthetic pathway of L-glutamic acid to produce a compound other than L-glutamic acid. Alternatively, a method of modifying the bacterium so that the activity of the further enzyme is reduced can also be mentioned. Examples of such enzymes include, but are not limited to, isocitrate lyase (aceA), α-ketoglutarate dehydrogenase (sucA), acetolactate synthase (ilvI), formate acetyltransferase (pfl), lactate dehydrogenase (ldh), alcohol dehydrogenase (Adh), glutamate decarboxylase (gadAB), succinate dehydrogenase (sdhABCD). Among these enzymes, for example, it is preferable to reduce or eliminate α-ketoglutarate dehydrogenase activity.

Escherichia bacteria with reduced or deficient α-ketoglutarate dehydrogenase activity and methods for obtaining them are described in US Pat. Nos. 5,378,616 and 5,573,945. In addition, a method for reducing or eliminating α-ketoglutarate dehydrogenase activity in enteric bacteria such as Pantoea bacteria, Enterobacter bacteria, Klebsiella bacteria, Erwinia bacteria, and the like are disclosed in U.S. Patent No. 6,197,559, U.S. Patent No. 6,682,912, This is disclosed in US Pat. No. 6,331,419, US Pat. No. 8,129,151, and WO2008 / 075483. Specific examples of bacteria belonging to the genus Escherichia with reduced or deficient α-ketoglutarate dehydrogenase activity include the following strains.
E. coli W3110sucA :: Kmr
E. coli AJ12624 (FERM BP-3853)
E. coli AJ12628 (FERM BP-3854)
E. coli AJ12949 (FERM BP-4881)

E. coli W3110sucA :: Kmr is a strain obtained by disrupting the sucA gene encoding the α-ketoglutarate dehydrogenase of E. coli W3110. This strain is completely deficient in α-ketoglutarate dehydrogenase activity.

In addition, L-glutamic acid-producing bacteria or parent strains for inducing them include Pantoea ananatis AJ13355 strain (FERM BP-6614), Pantoea ananatis SC17 strain (FERM BP-11091), Pantoea ananatis SC17 (0) strain (VKPM B) -9246) and the like. The AJ13355 strain is a strain isolated as a strain capable of growing on a medium containing L-glutamic acid and a carbon source at low pH from soil in Iwata City, Shizuoka Prefecture. The SC17 strain is a strain selected from the AJ13355 strain as a low mucus production mutant (US Pat. No. 6,596,517). On February 4, 2009, SC17 shares were incorporated by the National Institute of Advanced Industrial Science and Technology, Patent Biological Depositary Center (currently the National Institute of Technology and Evaluation, Patent Biological Depositary Center, ZIP Code: 292-0818, Address: Japan Kazusa Kamashizu 2-5-8-5120, Kisarazu City, Chiba Prefecture, Japan), and has been given the accession number FERM BP-11091. AJ13355 shares were founded on February 19, 1998 at the Institute of Biotechnology, National Institute of Advanced Industrial Science and Technology (currently the National Institute for Product Evaluation Technology, Patent Biological Depositary Center, Postal Code: 292-0818, Address: Chiba, Japan Deposited in Kazusa, Kazusa, Kazusa 2-5-8 120) under the deposit number FERM P-16644, transferred to an international deposit under the Budapest Treaty on January 11, 1999, and given the deposit number FERM BP-6614 Has been.

In addition, examples of L-glutamic acid-producing bacteria and parent strains for inducing them also include Pantoea bacteria with reduced or deficient α-ketoglutarate dehydrogenase activity. Such strains include the AJ13356 strain (US Pat. No. 6,331,419) which is the E1 subunit gene (sucA) deficient strain of the α-ketoglutarate dehydrogenase of the AJ13355 strain, and the SC17sucA strain which is the sucA gene deficient strain of the SC17 strain ( US Pat. No. 6,596,517). The AJ13356 strain was founded on February 19, 1998 at the Institute of Biotechnology, National Institute of Advanced Industrial Science and Technology (currently the National Institute for Product Evaluation Technology, Patent Biological Depositary Center, Postal Code: 292-0818, Address: Chiba, Japan. Deposited at Kisarazu City Kazusa Kamashichi 2-5-8 120) under the accession number FERM P-16645 and transferred to the international deposit under the Budapest Treaty on 11 January 1999 and given the accession number FERM BP-6616 ing. The SC17sucA strain was also assigned the private number AJ417. On February 26, 2004, the National Institute of Advanced Industrial Science and Technology, Patent Biological Deposit Center (now the National Institute for Product Evaluation Technology Patent Biological Deposit Center, postal code) : 292-0818, Address: Kazusa Kamashitsu 2-5-8 津 120, Kisarazu, Chiba, Japan), deposited under the accession number FERM BP-8646.

The AJ13355 strain was identified as Enterobacter agglomerans at the time of its isolation, but has recently been reclassified as Pantoea anaananatis by 16S rRNA nucleotide sequence analysis and the like. Therefore, the AJ13355 strain and the AJ13356 strain are deposited as Enterobacter agglomerans in the above depository organization, but are described as Pantoea ananatis in this specification.

Examples of L-glutamic acid-producing bacteria or parent strains for inducing them include Pantoea bacteria such as Pantoea ananatis SC17sucA / RSFCPG + pSTVCB strain, Pantoea ananatis AJ13601 strain, Pantoea ananatis NP106 strain, and Pantoea ananatis NA1 strain . The SC17sucA / RSFCPG + pSTVCB strain is different from the SC17sucA strain in that the plasmid RSFCPG containing the citrate synthase gene (gltA), the phosphoenolpyruvate carboxylase gene (ppc), and the glutamate dehydrogenase gene (gdhA) derived from Escherichia coli, and Brevi This is a strain obtained by introducing a plasmid pSTVCB containing a citrate synthase gene (gltA) derived from bacteria lactofermentum. The AJ13601 strain was selected from the SC17sucA / RSFCPG + pSTVCB strain as a strain resistant to a high concentration of L-glutamic acid at low pH. The NP106 strain is a strain obtained by removing the plasmid RSFCPG + pSTVCB from the AJ13601 strain. On August 18, 1999, AJ13601 shares were registered with the National Institute of Biotechnology, National Institute of Advanced Industrial Science and Technology (currently the National Institute for Product Evaluation Technology, Biological Depositary Center, Postal Code: 292-0818, Address: Chiba, Japan. Deposited at Kisarazu City Kazusa Kamashika 2-5-8 120) under the accession number FERM P-17516, transferred to an international deposit based on the Budapest Treaty on July 6, 2000 and given the accession number FERM BP-7207 ing.

Examples of L-glutamic acid-producing bacteria or parent strains for inducing them include strains in which both α-ketoglutarate dehydrogenase (sucA) activity and succinate dehydrogenase (sdh) activity are reduced or deficient (JP 2010) -041920). Specific examples of such a strain include a pantoeaPananatis NA1 sucAsdhA double-deficient strain (Japanese Patent Laid-Open No. 2010-041920).

In addition, examples of L-glutamic acid-producing bacteria or parent strains for inducing them include auxotrophic mutants. Specific examples of the auxotrophic mutant include E. coli VL334thrC ⁺ (VKPM B-8961) (EP 1172433). E. coli VL334 (VKPM B-1641) is an L-isoleucine and L-threonine auxotroph having a mutation in the thrC gene and the ilvA gene (US Pat. No. 4,278,765). E. coli VL334thrC ⁺ is an L-isoleucine-requiring L-glutamic acid-producing bacterium obtained by introducing a wild type allele of the thrC gene into VL334. The wild type allele of the thrC gene was introduced by a general transduction method using bacteriophage P1 grown on cells of wild type E. coli K12 strain (VKPM B-7).

In addition, examples of L-glutamic acid-producing bacteria or parent strains for inducing them also include strains resistant to aspartic acid analogs. These strains may be deficient in α-ketoglutarate dehydrogenase activity, for example. Specific examples of strains resistant to aspartate analogs and lacking α-ketoglutarate dehydrogenase activity include, for example, E. coli AJ13199 (FERM BP-5807) (US Pat. No. 5,908,768), and L-glutamic acid. E. coli FFRM P-12379 (US Pat. No. 5,393,671) and E. coli AJ13138 (FERM BP-5565) (US Pat. No. 6,110,714) are known.

As a method for imparting or enhancing L-glutamic acid-producing ability, for example, a bacterium is modified so that the activity of D-xylulose-5-phosphate-phosphoketolase and / or fructose-6-phosphate phosphoketolase is increased. There is also a method to do (Special Table 2008-509661). Either one or both of D-xylulose-5-phosphate-phosphoketolase activity and fructose-6-phosphate phosphoketolase activity may be enhanced. In the present specification, D-xylulose-5-phosphate phosphoketolase and fructose-6-phosphate phosphoketolase may be collectively referred to as phosphoketolase.

D-xylulose-5-phosphate-phosphoketolase activity is the consumption of phosphoric acid to convert xylulose-5-phosphate into glyceraldehyde-3-phosphate and acetyl phosphate, and one molecule of H ₂ O Means the activity of releasing. This activity is measured by the method described in Goldberg, M. et al. (Methods Enzymol., 9,515-520 (1966)) or L. Meile (J. Bacteriol. (2001) 183; 2929-2936). be able to.

In addition, fructose-6-phosphate phosphoketolase activity means that phosphoric acid is consumed, fructose 6-phosphate is converted into erythrose-4-phosphate and acetyl phosphate, and one molecule of H ₂ O is released. Means activity. This activity is measured by the method described in Racker, E (Methods Enzymol., 5, 276-280 (1962)) or L. Meile (J. Bacteriol. (2001) 183; 2929-2936). be able to.

Examples of a method for imparting or enhancing L-glutamic acid producing ability include, for example, enhancing expression of yhfK gene (WO2005 / 085419) and ybjL gene (WO2008 / 133161) which are L-glutamic acid excretion genes. It is done.

<L-glutamine producing bacteria>
Examples of the method for imparting or enhancing L-glutamine production ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-glutamine biosynthesis enzymes is increased. . Examples of such an enzyme include, but are not limited to, glutamate dehydrogenase (gdhA) and glutamine synthetase (glnA). The activity of glutamine synthetase may be enhanced by disrupting the glutamine adenylyltransferase gene (glnE) or the PII regulatory protein gene (glnB) (EP1229121).

The method for imparting or enhancing L-glutamine production ability is, for example, selected from an enzyme that catalyzes a reaction that branches from the biosynthetic pathway of L-glutamine to produce a compound other than L-glutamine. Alternatively, a method of modifying the bacterium so that the activity of the further enzyme is reduced can also be mentioned. Such an enzyme is not particularly limited, and includes glutaminase.

Examples of L-glutamine producing bacteria or parent strains for inducing them include strains belonging to the genus Escherichia having a mutant glutamine synthetase in which the tyrosine residue at position 397 of glutamine synthetase is substituted with another amino acid residue. (US Patent Application Publication No. 2003-0148474).

<L-proline producing bacteria>
Examples of the method for imparting or enhancing L-proline production ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-proline biosynthesis enzymes is increased. . Such enzymes include glutamate-5-kinase (proB), γ-glutamyl-phosphate reductase, pyrroline-5-carboxylate reductase (putA). For the enhancement of the enzyme activity, for example, the proB gene (German Patent No. 3127361) encoding glutamate-5-kinase in which feedback inhibition by L-proline is released can be suitably used.

In addition, as a method for imparting or enhancing L-proline production ability, for example, a method of modifying bacteria so that the activity of an enzyme involved in L-proline degradation is reduced. Examples of such an enzyme include proline dehydrogenase and ornithine aminotransferase.

Specific examples of L-proline-producing bacteria or parent strains for deriving them include, for example, E. coli NRRL B-12403 and NRRL B-12404 (British Patent No. 2075056), E. coli VKPM B-8012 ( Russian patent application 2000124295), E. coli plasmid variant described in German Patent 3127361, Bloom FR et al (The 15th Miami winter symposium, 1983, p.34), E. coli plasmid variant, 3, E. coli 702 strain (VKPMB-8011) resistant to 4-dehydroxyproline and azatidine-2-carboxylate, E. coli 702ilvA strain (VKPM B-8012) (EP 1172433) which is a 702 ilvA gene-deficient strain Is mentioned.

<L-threonine producing bacteria>
Examples of the method for imparting or enhancing the ability to produce L-threonine include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-threonine biosynthetic enzymes is increased. . Examples of such enzymes include, but are not limited to, aspartokinase III (lysC), aspartate semialdehyde dehydrogenase (asd), aspartokinase I (thrA), homoserine kinase (thrB), threonine synthase ( threonine synthase) (thrC), aspartate aminotransferase (aspartate transaminase) (aspC). Among these enzymes, it enhances the activity of one or more enzymes selected from aspartokinase III, aspartate semialdehyde dehydrogenase, aspartokinase I, homoserine kinase, aspartate aminotransferase, and threonine synthase. Is preferred. The L-threonine biosynthesis gene may be introduced into a strain in which threonine degradation is suppressed. Examples of strains in which threonine degradation is suppressed include E. coli TDH6 strain lacking threonine dehydrogenase activity (Japanese Patent Laid-Open No. 2001-346578).

The activity of the L-threonine biosynthetic enzyme is inhibited by the final product L-threonine. Therefore, in order to construct an L-threonine-producing bacterium, it is preferable to modify the L-threonine biosynthetic gene so that it is not subject to feedback inhibition by L-threonine. The thrA, thrB, and thrC genes constitute a threonine operon, and the threonine operon forms an attenuator structure. Expression of the threonine operon is inhibited by isoleucine and threonine in the culture medium, and is suppressed by attenuation. Enhanced expression of the threonine operon can be achieved by removing the leader sequence or attenuator in the attenuation region (Lynn, S. P., Burton, W. S., Donohue, T. J., Gould, R. M., Gumport, R. I., and Gardner, J. F. J. Mol. Biol. 194: 59-69 1987 (1987); WO02 / 26993; WO2005 / 049808; WO2003 / 097839).

A unique promoter exists upstream of the threonine operon, but this promoter may be replaced with a non-natural promoter (see pamphlet of WO98 / 04715). In addition, the threonine operon may be constructed so that a gene involved in threonine biosynthesis is expressed under the control of a lambda phage repressor and promoter (see European Patent No. 0593792). Bacteria modified so as not to be subjected to feedback inhibition by L-threonine can also be obtained by selecting a strain resistant to α-amino-β-hydroxyvaleric acid (AHV), which is an L-threonine analog.

Thus, the threonine operon modified so as not to be subjected to feedback inhibition by L-threonine is improved in the expression level in the host by increasing the copy number or being linked to a strong promoter. Is preferred. An increase in copy number can be achieved by introducing a plasmid containing a threonine operon into the host. An increase in copy number can also be achieved by transferring the threonine operon onto the host genome using a transposon, Mu phage, or the like.

In addition, examples of a method for imparting or enhancing L-threonine production ability include a method for imparting L-threonine resistance to a host and a method for imparting L-homoserine resistance. The imparting of resistance can be achieved, for example, by enhancing the expression of a gene that imparts resistance to L-threonine or a gene that imparts resistance to L-homoserine. Examples of genes that confer resistance include rhtA gene (Res. Microbiol. 154: 123-135 (2003)), rhtB gene (European Patent Application Publication No. 0994190), rhtC gene (European Patent Application Publication No. 1013765) ), YfiK gene, and yeaS gene (European Patent Application Publication No. 1016710). For methods for imparting L-threonine resistance to a host, methods described in European Patent Application Publication No. 0994190 and International Publication No. 90/04636 can be referred to.

Specific examples of L-threonine-producing bacteria or parent strains for deriving them include, for example, E. coli TDH-6 / pVIC40 (VKPM B-3996) (US Patent No. 5,175,107, US Patent No. 5,705,371), E. coli 472T23 / pYN7 (ATCC 98081) (U.S. Patent No. 5,631,157), E. coli NRRL-21593 (U.S. Patent No. 5,939,307), E. coli FERM BP-3756 (U.S. Patent No. 5,474,918), E. coli FERM BP-3519 and FERM BP-3520 (U.S. Patent No. 5,376,538), E. coli MG442 (Gusyatiner et al., Genetika (in Russian), 14, 947-956 (1978)), E. coli VL643 and VL2055 ( EP 1149911 A), and E. coli VKPM B-5318 (EP 0593792 B).

VKPM B-3996 strain is a strain obtained by introducing plasmid pVIC40 into TDH-6 strain. The TDH-6 strain is sucrose-assimilating, lacks the thrC gene, and has a leaky mutation in the ilvA gene. The VKPM B-3996 strain has a mutation that imparts resistance to a high concentration of threonine or homoserine in the rhtA gene. The plasmid pVIC40 is a plasmid in which a thrA ^* BC operon containing a mutant thrA gene encoding an aspartokinase homoserine dehydrogenase I resistant to feedback inhibition by threonine and a wild type thrBC gene is inserted into an RSF1010-derived vector (US Patent) No. 5,705,371). This mutant thrA gene encodes aspartokinase homoserine dehydrogenase I substantially desensitized to feedback inhibition by threonine. B-3996 was deposited on 19 November 1987 at the All Union Scientific Center of Antibiotics (Nagatinskaya Street 3-A, 117105 Moscow, Russia) with accession number RIA 1867. . This stock was also assigned to the Lucian National Collection of Industrial Microorganisms (VKPM) on April 7, 1987, under the accession number VKPM (FGUP GosNII Genetika, 1 Dorozhny proezd., 1 Moscow 117545, Russia). Deposited at B-3996.

The strain VKPM B-5318 is non-isoleucine-requiring and retains the plasmid pPRT614 in which the control region of the threonine operon in the plasmid pVIC40 is replaced with a temperature-sensitive lambda phage C1 repressor and a PR promoter. VKPM B-5318 was assigned to Lucian National Collection of Industrial Microorganisms (VKPM) 3 (FGUP GosNII Genetika, 1 Dorozhny proezd., 1 Moscow 117545, 1990Russia) on May 3, 1990. Deposited internationally at B-5318.

The thrA gene encoding aspartokinase homoserine dehydrogenase I of E. coli has been elucidated (nucleotide numbers 337-2799, GenBank accession NC — 000913.2, gi: 49175990). The thrA gene is located between the thrL gene and the thrB gene in the chromosome of E. coli K-12. The thrB gene encoding the homoserine kinase of Escherichia coli has been elucidated (nucleotide numbers 2801 to 3733, GenBank accession NC — 000913.2, gi: 49175990). The thrB gene is located between the thrA gene and the thrC gene in the chromosome of E. coli K-12. The thrC gene encoding threonine synthase from E. coli has been elucidated (nucleotide numbers 3734-5020, GenBank accession NC — 000913.2, gi: 49175990). The thrC gene is located between the thrB gene and the yaaX open reading frame in the chromosome of E. coli K-12. In addition, a thrA ^* BC operon containing a mutant thrA gene encoding an aspartokinase homoserine dehydrogenase I resistant to feedback inhibition by threonine and a wild type thrBC gene is known in the threonine-producing strain E. coli VKPM B-3996. It can be obtained from plasmid pVIC40 (US Pat. No. 5,705,371).

The rhtA gene of E. coli is present at 18 minutes of the E. coli chromosome close to the glnHPQ operon, which encodes a glutamine transport system element. The rhtA gene is the same as ORF1 (ybiF gene, nucleotide numbers 764 to 1651, GenBank accession number AAA218541, gi: 440181), and is located between the pexB gene and the ompX gene. The unit that expresses the protein encoded by ORF1 is called rhtA gene (rht: resistant toosehomoserine andeonthreonine (resistant to homoserine and threonine)). It has also been found that the rhtA23 mutation conferring resistance to high concentrations of threonine or homoserine is a G → A substitution at position -1 relative to the ATG initiation codon (ABSTRACTS of the 17th International Congress of Biochemistry and Molecular Biology in conjugation with Annual Meeting of the American Society for Biochemistry and Molecular Biology, San Francisco, California August 24-29, 1997, abstract No. 457, EP 1013765 A).

The asd gene of E. coli has already been clarified (nucleotide numbers 3572511 to 3571408, GenBank accession NC_000913.1, gi: 16131307), and can be obtained by PCR using primers prepared based on the nucleotide sequence of the gene ( White, TJ et al., Trends Genet., 5, 185 (1989)). The asd gene of other microorganisms can be obtained similarly.

In addition, the aspC gene of E. 既に coli has already been clarified (nucleotide numbers 983742 to 984932, GenBank accession NC_000913.1, gi: 16128895), and obtained by PCR using a primer prepared based on the nucleotide sequence of the gene be able to. The aspC gene of other microorganisms can be obtained similarly.

<L-lysine producing bacteria>
Examples of a method for imparting or enhancing L-lysine production ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-lysine biosynthesis enzymes is increased. . Such enzymes include, but are not limited to, dihydrodipicolinate synthase (dapA), aspartokinase III (lysC), dihydrodipicolinate reductase (dapB), diaminopimelate Diaminopimelate decarboxylase (lysA), diaminopimelate dehydrogenase (ddh) (US Pat. No. 6,040,160), phosphoenolpyrvate carboxylase (ppc), aspartate semialdehyde dehydrogenase ) (Asd), aspartate aminotransferase (aspartate transaminase) (aspC), diaminopimelate epi Diaminopimelate epimerase (dapF), tetrahydrodipicolinate succinylase (dapD), succinyl-diaminopimelate deacylase (dapE), and aspartase (aspA) (195) ). Among these enzymes, for example, dihydrodipicolinate reductase, diaminopimelate decarboxylase, diaminopimelate dehydrogenase, phosphoenolpyruvate carboxylase, aspartate aminotransferase, diaminopimelate epimerase, aspartate semialdehyde dehydrogenase, tetrahydrodipicolinate succinylase, and Preferably, the activity of one or more enzymes selected from succinyl diaminopimelate deacylase is enhanced. In addition, in L-lysine producing bacteria or a parent strain for deriving the same, a gene (cyo) (EP 1170376 A) involved in energy efficiency, a gene encoding nicotinamide nucleotide transhydrogenase (pntAB) ( US Pat. No. 5,830,716), ybjE gene (WO2005 / 073390), or combinations thereof may have increased expression levels. Aspartokinase III (lysC) is subject to feedback inhibition by L-lysine. To enhance the activity of the enzyme, a mutant lysC gene encoding aspartokinase III that has been desensitized to feedback inhibition by L-lysine is used. It may be used (US Pat. No. 5,932,453). In addition, since it is subjected to feedback inhibition by dihydrodipicolinate synthase (dapA) L-lysine, in order to enhance the activity of the enzyme, a mutant type encoding dihydrodipicolinate synthase from which feedback inhibition by L-lysine is released The dapA gene may be used.

The method for imparting or enhancing L-lysine production ability is, for example, selected from enzymes that catalyze the reaction of branching from the biosynthetic pathway of L-lysine to produce compounds other than L-lysine. Alternatively, a method of modifying the bacterium so that the activity of the further enzyme is reduced can also be mentioned. Such enzymes include, but are not limited to, homoserine dehydrogenase, lysine decarboxylase (US Pat. No. 5,827,698), and malic enzyme (WO2005 / 010175). .

In addition, examples of L-lysine-producing bacteria or parent strains for inducing them include mutants having resistance to L-lysine analogs. L-lysine analogs inhibit the growth of bacteria such as Enterobacteriaceae and coryneform bacteria, but this inhibition is completely or partially released when L-lysine is present in the medium. The L-lysine analog is not particularly limited, and examples thereof include oxalysine, lysine hydroxamate, S- (2-aminoethyl) -L-cysteine (AEC), γ-methyllysine, and α-chlorocaprolactam. Mutant strains having resistance to these lysine analogs can be obtained by subjecting bacteria to normal artificial mutation treatment.

Specific examples of L-lysine-producing bacteria or parent strains for deriving them include, for example, E. coli AJ11442 (FERM BP-1543, NRRL B-12185; see U.S. Pat. No. 4,346,170) and E. coli VL611. Can be mentioned. In these strains, feedback inhibition of aspartokinase by L-lysine is released.

Specific examples of L-lysine-producing bacteria or parent strains for inducing them include E. coli WC196 strain. The WC196 strain was bred by conferring AEC resistance to the W3110 strain derived from E. coli K-12 (US Pat. No. 5,827,698). The WC196 strain was named E. coli AJ13069, and on December 6, 1994, the Institute of Biotechnology, National Institute of Advanced Industrial Science and Technology (currently the National Institute for Product Evaluation Technology, Patent Biological Depositary Center, ZIP Code: 292- 0818, address: 2-5-8 鎌 120, Kazusa Kamashitsu, Kisarazu City, Chiba, Japan), deposited under the accession number FERM P-14690, transferred to an international deposit based on the Budapest Treaty on September 29, 1995. No. FERM BP-5252 (US Pat. No. 5,827,698).

Preferred L-lysine producing bacteria include E.coli WC196ΔcadAΔldc and E.coli WC196ΔcadAΔldc / pCABD2 (WO2010 / 061890). WC196ΔcadAΔldc is a strain constructed by disrupting the cadA and ldcC genes encoding lysine decarboxylase from the WC196 strain. WC196ΔcadAΔldc / pCABD2 is a strain constructed by introducing plasmid pCABD2 (US Pat. No. 6,040,160) containing a lysine biosynthesis gene into WC196ΔcadAΔldc. WC196ΔcadAΔldc was named AJ110692, and on October 7, 2008, National Institute of Advanced Industrial Science and Technology, Patent Biological Deposit Center (currently, National Institute of Technology and Evaluation, Patent Biological Deposit Center, ZIP Code: 292-0818 , Address: 2-5-8 Kazusa, Kazusa Kamashitsu, Kisarazu, Chiba, Japan) Room No. FERM BP-11027. pCABD2 is a mutant dapA gene encoding dihydrodipicolinate synthase (DDPS) derived from Escherichia coli having a mutation that is desensitized to feedback inhibition by L-lysine, and a mutation that is desensitized to feedback inhibition by L-lysine. A mutant lysC gene encoding aspartokinase III derived from Escherichia coli, dapB gene encoding dihydrodipicolinate reductase derived from Escherichia coli, and ddh encoding a diaminopimelate dehydrogenase derived from Brevibacterium lactofermentum Contains genes.

A preferable L-lysine-producing bacterium includes E.coli AJIK01 strain (NITE BP-01520). The AJIK01 strain was named E. coli AJ111046. On January 29, 2013, the National Institute of Technology and Evaluation, Patent Microorganisms Deposit Center (Postal Code: 292-0818, Address: Kazusa Kama, Kisarazu City, Chiba Prefecture, Japan) No. 2-5-8 122), transferred to an international deposit under the Budapest Treaty on May 15, 2014, and assigned the deposit number NITE BP-01520.

<L-arginine producing bacteria>
Examples of the method for imparting or enhancing L-arginine-producing ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-arginine biosynthesis enzymes is increased. . Examples of such enzymes include, but are not limited to, N-acetylglutamate synthase (argA), N-acetylglutamylphosphate reductase (argC), ornithine acetyltransferase (argJ), N-acetylglutamate kinase (argB), acetylornithine Examples include transaminase (argD), acetylornithine deacetylase (argE) ornithine carbamoyltransferase (argF), argininosuccinate synthase (argG), argininosuccinate lyase (argH), and carbamoyl phosphate synthase (carAB). Examples of the N-acetylglutamate synthase (argA) gene include mutant N-acetylglutamate synthase in which amino acid residues corresponding to the 15th to 19th positions of the wild type are substituted and feedback inhibition by L-arginine is released. It is preferable to use a gene to be encoded (European Application Publication No. 1170361).

Specific examples of L-arginine-producing bacteria or parent strains for deriving them include, for example, E. coli 237 strain (VKPM B-7925) (US Patent Application Publication 2002/058315 A1), mutant N-acetylglutamate Its derivative strain され (Russian patent application No. 2001112869, EP1170361A1) introduced with the argA gene encoding synthase, E.237coli 382 strain (VKPM B-7926) 237 (VKPM B-7926) EP1170358A1) and E. coli 382ilvA + strain, which is a strain in which the wild-type ilvA gene derived from E. coli K-12 strain is introduced into 382 strain. E. coli 237 shares will be transferred to VKPM B- on April 10, 2000 at Lucian National Collection of Industrial Microorganisms (VKPM) (FGUP GosNII Genetika, 1 Dorozhny proezd., 1 Moscow 117545, Russia). Deposited with a deposit number of 7925 and transferred to an international deposit under the Budapest Treaty on 18 May 2001. E. coli 382 shares were established on April 10, 2000 at Lucian National Collection of Industrial Microorganisms (VKPM) (FGUP GosNII Genetika, 1 Dorozhny proezd., 1 Moscow 117545, Russia). Deposited with 7926 accession number.

In addition, examples of L-arginine-producing bacteria or parent strains for inducing them include strains having resistance to amino acid analogs and the like. Such strains include, for example, α-methylmethionine, p-fluorophenylalanine, D-arginine, arginine hydroxamic acid, S- (2-aminoethyl) -cysteine, α-methylserine, β-2-thienylalanine, or Examples include Escherichia coli mutants having resistance to sulfaguanidine (see JP-A-56-106598).

<L-citrulline-producing bacteria and L-ornithine-producing bacteria>
L-citrulline and L-ornithine share a biosynthetic pathway with L-arginine. Thus, N-acetylglutamate synthase (argA), N-acetylglutamylphosphate reductase (argC), ornithine acetyltransferase (argJ), N-acetylglutamate kinase (argB), acetylornithine transaminase (argD), and / or acetylornithine By increasing the enzyme activity of deacetylase (argE), the ability to produce L-citrulline and / or L-ornithine can be imparted or enhanced (WO 2006-35831).

<L-histidine producing bacteria>
Examples of the method for imparting or enhancing L-histidine production ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-histidine biosynthesis enzymes is increased. . Examples of such an enzyme include, but are not limited to, ATP phosphoribosyltransferase (hisG), phosphoribosyl-AMP cyclohydrolase (hisI), phosphoribosyl-ATP pyrophosphohydrolase (hisI), phosphoribosylformimino-5-aminoimidazole carboxamide ribonucleoside. Examples thereof include tide isomerase (hisA), amide transferase (hisH), histidinol phosphate aminotransferase (hisC), histidinol phosphatase (hisB), and histidinol dehydrogenase (hisD).

Of these, L-histidine biosynthetic enzymes encoded by hisG and hisBHAFI are known to be inhibited by L-histidine. Therefore, the ability to produce L-histidine can be imparted or enhanced by introducing a mutation that confers resistance to feedback inhibition in, for example, the ATP phosphoribosyltransferase gene (hisG) (Russian Patent No. 2003677 and No. 2). 2119536).

Specific examples of L-histidine-producing bacteria or parent strains for inducing them include, for example, E. coli 24 strain (VKPM B-5945, RU2003677), E. coli NRRL B-12116-B-12121 (US Patent) No. 4,388,405), E. coli H-9342 (FERM BP-6675) and H-9343 (FERM BP-6676) (U.S. Patent No. 6,344,347), E. coli H-9341 (FERM BP-6674) (EP1085087) E. coli AI80 / pFM201 (US Pat. No. 6,258,554), E. coli FERM P-5038 and 5048 into which a vector carrying DNA encoding an L-histidine biosynthetic enzyme was introduced (Japanese Patent Laid-Open No. 56-005099) ), E. coli strain (EP1016710A) introduced with a gene for amino acid transport, E. coli 80 strain (VKPM B) with resistance to sulfaguanidine, DL-1,2,4-triazole-3-alanine, and streptomycin -7270, (Russian Patent No. 2119536) and other strains belonging to the genus Escherichia.

<L-cysteine producing bacteria>
Examples of the method for imparting or enhancing L-cysteine production ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-cysteine biosynthesis enzymes is increased. . Examples of such an enzyme include, but are not limited to, serine acetyltransferase (cysE) and 3-phosphoglycerate dehydrogenase (serA). Serine acetyltransferase activity can be enhanced, for example, by introducing a mutant cysE gene encoding a mutant serine acetyltransferase resistant to feedback inhibition by cysteine into bacteria. Mutant serine acetyltransferases are disclosed, for example, in JP-A-11-155571 and US Patent Publication No. 20050112731. Further, the 3-phosphoglycerate dehydrogenase activity can be enhanced by introducing, for example, a mutant serA gene encoding a mutant 3-phosphoglycerate dehydrogenase resistant to feedback inhibition by serine into a bacterium. Mutant 3-phosphoglycerate dehydrogenase is disclosed, for example, in US Pat. No. 6,180,373.

The method for imparting or enhancing L-cysteine production ability is selected from, for example, an enzyme that catalyzes a reaction that branches from the biosynthesis pathway of L-cysteine to produce a compound other than L-cysteine. Alternatively, a method of modifying the bacterium so that the activity of the further enzyme is reduced can also be mentioned. Examples of such enzymes include enzymes involved in the degradation of L-cysteine. The enzyme involved in the degradation of L-cysteine is not particularly limited, but cystathionine-β-lyase (metC) (Japanese Patent Laid-Open No. 11-155571, Chandra et. Al., Biochemistry, 21 (1982) 3064-3069)) Tryptophanase (tnaA) (Japanese Patent Laid-Open No. 2003-169668, Austin 、 Newton et. Al., J. Biol. Chem. 240 (1965) 1211-1218), O-acetylserine sulfhydrylase B (cysM) (special JP 2005-245311), malY gene product (JP 2005-245311), d0191 gene product of Pantoea 遺伝子 ananatis (JP 2009-232844).

In addition, examples of methods for imparting or enhancing L-cysteine production ability include enhancing the L-cysteine excretion system and enhancing the sulfate / thiosulfate transport system. Examples of proteins of the L-cysteine excretion system include proteins encoded by the ydeD gene (JP 2002-233384), proteins encoded by the yfiK gene (JP 2004-49237), emrAB, emrKY, yojIH, acrEF, bcr, And each protein encoded by each gene of cusA (Japanese Patent Laid-Open No. 2005-287333), and protein encoded by the yeaS gene (Japanese Patent Laid-Open No. 2010-187552). Examples of the sulfate / thiosulfate transport system protein include proteins encoded by the cysPTWAM gene cluster.

Specific examples of L-cysteine-producing bacteria or parent strains for deriving them include, for example, E. coli JM15 (US Patent) transformed with various cysE alleles encoding mutant serine acetyltransferase resistant to feedback inhibition. No. 6,218,168, Russian Patent Application No. 2003121601), E. coli W3110 (US Pat.No. 5,972,663), cysteine desulfhydrase, which has an overexpressed gene encoding a protein suitable for excretion of substances toxic to cells Examples include E. coli strain (JP11155571A2) with reduced activity and E. coli W3110 (WO01 / 27307A1) with increased activity of the transcriptional control factor of the positive cysteine regulon encoded by the cysB gene.

<L-methionine producing bacteria>
Examples of L-methionine-producing bacteria or parent strains for inducing them include L-threonine-requiring strains and mutants having resistance to norleucine (Japanese Patent Laid-Open No. 2000-139471). In addition, examples of L-methionine-producing bacteria or parent strains for deriving them also include strains that retain mutant homoserine transsuccinylase that is resistant to feedback inhibition by L-methionine (Japanese Patent Laid-Open No. 2000-139471). , US20090029424). Since L-methionine is biosynthesized with L-cysteine as an intermediate, L-methionine production ability can be improved by improving L-cysteine production ability (Japanese Patent Laid-Open No. 2000-139471, US20080311632).

Specific examples of L-methionine-producing bacteria or parent strains for inducing them include, for example, E. coli AJ11539 (NRRL B-12399), E. coli AJ11540 (NRRL B-12400), E. coli AJ11541 (NRRL B-12401), E. coli AJ11542 (NRRL B-12402) (British Patent No. 2075055), E. coli 218 strain (VKPM B-8125) having resistance to norleucine, an analog of L-methionine (Russian Patent No. 2209248) No.), 73 shares (VKPM B-8126) (Russian Patent No. 2215782), E. coli AJ13425 (FERM P-16808) (Japanese Patent Laid-Open No. 2000-139471). The AJ13425 strain lacks a methionine repressor, weakens intracellular S-adenosylmethionine synthetase activity, and produces intracellular homoserine transsuccinylase activity, cystathionine γ-synthase activity, and aspartokinase-homoserine dehydrogenase II. L-threonine-requiring strain derived from E. coli W3110 with enhanced activity.

<L-leucine producing bacteria>
Examples of the method for imparting or enhancing the ability to produce L-leucine include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-leucine biosynthesis enzymes is increased. . Examples of such an enzyme include, but are not limited to, an enzyme encoded by a gene of leuABCD operon. For enhancing enzyme activity, for example, a mutant leuA gene (US Pat. No. 6,403,342) encoding isopropyl malate synthase from which feedback inhibition by L-leucine has been released can be suitably used.

Specific examples of L-leucine-producing bacteria or parent strains for inducing the same include, for example, leucine-resistant E. coli strains (eg, 57 strains (VKPM B-7386, US Pat. No. 6,124,121)), β- E. coli strains resistant to leucine analogs such as 2-thienylalanine, 3-hydroxyleucine, 4-azaleucine, 5,5,5-trifluoroleucine (JP-B-62-34397 and JP-A-8-70879), WO96 And strains belonging to the genus Escherichia such as E. coli strain and E. coli H-9068 (JP-A-8-70879) obtained by the genetic engineering method described in / 06926.

<L-isoleucine producing bacterium>
Examples of the method for imparting or enhancing L-isoleucine producing ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-isoleucine biosynthesis enzymes is increased. . Examples of such an enzyme include, but are not limited to, threonine deaminase and acetohydroxy acid synthase (JP-A-2-458, FR 0356739, and US Pat. No. 5,998,178).

Specific examples of L-isoleucine-producing bacteria or parent strains for inducing them include mutants having resistance to 6-dimethylaminopurine (Japanese Patent Laid-Open No. 5-304969), thiisoleucine, isoleucine hydroxamate, etc. And an Escherichia bacterium such as a mutant strain resistant to DL-ethionine and / or arginine hydroxamate in addition to the isoleucine analog (Japanese Patent Laid-Open No. 5-130882).

<L-valine producing bacteria>
Examples of a method for imparting or enhancing L-valine production ability include a method of modifying a bacterium so that the activity of one or more enzymes selected from L-valine biosynthetic enzymes is increased. . Examples of such enzymes include, but are not limited to, enzymes encoded by genes of ilvGMEDA operon and ilvBNC operon. ilvBN encodes acetohydroxy acid synthase, and ilvC encodes isomeroreductase (WO 00/50624). The ilvGMEDA operon and the ilvBNC operon are subject to expression suppression (attenuation) by L-valine, L-isoleucine, and / or L-leucine. Therefore, in order to enhance the enzyme activity, it is preferable to remove or modify the region necessary for attenuation and to cancel the expression suppression by the produced L-valine. The threonine deaminase encoded by the ilvA gene is an enzyme that catalyzes the deamination reaction from L-threonine to 2-ketobutyric acid, which is the rate-limiting step of the L-isoleucine biosynthesis system. Therefore, for L-valine production, it is preferable that the ilvA gene is disrupted and the threonine deaminase activity is reduced.

The method for imparting or enhancing L-valine-producing ability is, for example, selected from enzymes that catalyze a reaction that branches from the biosynthetic pathway of L-valine to produce a compound other than L-valine. Alternatively, a method of modifying the bacterium so that the activity of the further enzyme is reduced can also be mentioned. Examples of such enzymes include, but are not limited to, threonine dehydratase involved in L-leucine synthesis and enzymes involved in D-pantothenic acid synthesis (International Publication No. 00/50624).

Specific examples of the L-valine-producing bacterium or the parent strain for deriving the same include, for example, the E. coli strain (US Pat. No. 5,998,178) that has been modified to overexpress the ilvGMEDA operon.

In addition, examples of L-valine-producing bacteria and parent strains for deriving the same also include strains having mutations in aminoacyl t-RNA synthetase (US Pat. No. 5,658,766). Examples of such a strain include E. coli VL1970 having a mutation in the ileS gene encoding isoleucine tRNA synthetase. E. coli VL1970 was registered with the accession number VKPM on June 24, 1988 in the Lucian National Collection of Industrial Microorganisms (VKPM) (FGUP GosNII Genetika, 1 Dorozhny proezd., 1 Moscow 117545, Russia). Deposited at B-4411. In addition, examples of L-valine-producing bacteria or parent strains for deriving the same also include mutant strains (WO96 / 06926) that require lipoic acid for growth and / or lack H ⁺ -ATPase. .

<L-tryptophan producing bacteria, L-phenylalanine producing bacteria, L-tyrosine producing bacteria>
Examples of methods for imparting or enhancing L-tryptophan production ability, L-phenylalanine production ability, and / or L-tyrosine production ability include biosynthesis of L-tryptophan, L-phenylalanine, and / or L-tyrosine. Examples include a method of modifying a bacterium so that the activity of one or more enzymes selected from system enzymes is increased.

Biosynthetic enzymes common to these aromatic amino acids are not particularly limited, but 3-deoxy-D-arabinohepturonic acid-7-phosphate synthase (aroG), 3-dehydroquinate synthase (aroB) Shikimate dehydrogenase (aroE), shikimate kinase (aroL), 5-enolic acid pyruvylshikimate 3-phosphate synthase (aroA), chorismate synthase (aroC) (European Patent No. 763127). Expression of genes encoding these enzymes is controlled by a tyrosine repressor (tyrR), and the activity of these enzymes may be enhanced by deleting the tyrR gene (European Patent No. 763127).

Examples of the L-tryptophan biosynthesis enzyme include, but are not limited to, anthranilate synthase (trpE), tryptophan synthase (trpAB), and phosphoglycerate dehydrogenase (serA). For example, L-tryptophan production ability can be imparted or enhanced by introducing DNA containing a tryptophan operon. Tryptophan synthase consists of α and β subunits encoded by trpA and trpB genes, respectively. Since anthranilate synthase is subject to feedback inhibition by L-tryptophan, in order to enhance the activity of the enzyme, a gene encoding the enzyme into which a mutation that releases feedback inhibition is introduced may be used. Since phosphoglycerate dehydrogenase is feedback-inhibited by L-serine, a gene encoding the enzyme into which a mutation that releases feedback inhibition is introduced may be used to enhance the activity of the enzyme. Furthermore, L-tryptophan-producing ability is imparted or enhanced by increasing the expression of an operon consisting of malate synthase (aceB), isocitrate lyase (aceA), and isocitrate dehydrogenase kinase / phosphatase (aceK). (WO2005 / 103275).

The L-phenylalanine biosynthetic enzyme is not particularly limited, and examples thereof include chorismate mutase and prefenate dehydratase. Chorismate mutase and prefenate dehydratase are encoded by the pheA gene as a bifunctional enzyme. Since chorismate mutase-prefenate dehydratase is feedback-inhibited by L-phenylalanine, in order to enhance the activity of the enzyme, a gene encoding the enzyme into which a mutation that releases feedback inhibition is introduced may be used.

The L-tyrosine biosynthetic enzyme is not particularly limited, and examples thereof include chorismate mutase and prephenate dehydrogenase. Chorismate mutase and prefenate dehydrogenase are encoded by the tyrA gene as a bifunctional enzyme. Since chorismate mutase-prefenate dehydrogenase is feedback-inhibited by L-tyrosine, to enhance the activity of the enzyme, a gene encoding the enzyme into which a mutation that releases feedback inhibition is introduced may be used.

The L-tryptophan, L-phenylalanine, and / or L-tyrosine producing bacterium may be modified so that biosynthesis of aromatic amino acids other than the target aromatic amino acid is lowered. In addition, L-tryptophan, L-phenylalanine, and / or L-tyrosine-producing bacteria may be modified so that the by-product uptake system is enhanced. By-products include aromatic amino acids other than the desired aromatic amino acid. Examples of genes encoding uptake systems of by-products include, for example, uptake systems of tnaB and mtr, which are L-tryptophan uptake systems, and pheP, L-tyrosine, which are genes encoding uptake systems of L-phenylalanine. TyrP, which is a gene coding for (EP1484410).

As an L-tryptophan-producing bacterium or a parent strain for deriving it, specifically, for example, E. coli JP4735 / pMU3028 carrying a mutant trpS gene encoding a partially inactivated tryptophanyl-tRNA synthetase. DSM10122) and JP6015 / pMU91 (DSM10123) (U.S. Patent No. 5,756,345), E. coli SV164 with trpE allele encoding anthranilate synthase not subject to feedback inhibition by tryptophan, phosphoglycerate dehydrogenase not subject to feedback inhibition by serine E. coli SV164 (pGH5) (U.S. Pat.No. 6,180,373) with serA allele encoding and trpE allele encoding anthranilate synthase not subject to feedback inhibition by tryptophan, coding for anthranilate synthase not subject to feedback inhibition by tryptophan A strain introduced with a tryptophan operon containing a trpE allele (JP 57-71397, JP 62-244382, U.S. Pat.No. 4,371,614), E. coliGX AGX17 (pGX44) lacking tryptophanase NRRL B-12263) and AGX6 (pGX50) aroP (NRRL B-12264) (U.S. Pat.No. 4,371,614), E. coli AGX17 / pGX50, pACKG4-pps (WO9708333, U.S. Patent No. No. 6,319,696), strains belonging to the genus Escherichia with increased activity of the protein encoded by the yedA gene or the yddG gene (US Patent Application Publications 2003/0148473 A1 and 2003/0157667 A1).

As an L-phenylalanine producing bacterium or a parent strain for deriving the same, specifically, for example, E. coli AJ12739 (tyrA :: Tn10, tyrR) (VKPM) lacking chorismate mutase-prefenate dehydrogenase and tyrosine repressor B-8197) (WO03 / 044191), E. coli HW1089 (ATCC 55371) (U.S. Patent No. 5,354,672), carrying a mutant pheA34 gene encoding chorismate mutase-prefenate dehydratase with released feedback inhibition (US Patent No. 5,354,672), E .Coli MWEC 101-b (KR8903681), E.coli NRRL B-12141, NRRL B-12145, NRRL B-12146, NRRL B-12147 (US Pat. No. 4,407,952). Further, as an L-phenylalanine-producing bacterium or a parent strain for deriving the same, specifically, for example, E. coli K-12 that retains a gene encoding chorismate mutase-prefenate dehydratase in which feedback inhibition is released. <W3110 (tyrA) / pPHAB> (FERM BP-3566), E. coli K-12 <W3110 (tyrA) / pPHAD> (FERM BP-12659), E. coli K-12 <W3110 (tyrA) / pPHATerm> (FERM BP-12662), E. coli K-12 AJ 12604 <W3110 (tyrA) / pBR-aroG4, pACMAB> (FERM BP-3579) (EP 488424 B1). Specific examples of L-phenylalanine-producing bacteria or parent strains for inducing them include, for example, strains belonging to the genus Escherichia in which the activity of the protein encoded by the yedA gene or the yddG gene is increased (US2003 / 0148473, US2003 / 0157667, WO03 / 044192).

In addition, examples of a method for imparting or enhancing L-amino acid-producing ability include a method of modifying a bacterium so that the activity of discharging L-amino acid from the bacterium cell is increased. The activity to excrete L-amino acids can be increased, for example, by increasing the expression of a gene encoding a protein that excretes L-amino acids. Examples of genes encoding proteins that excrete various amino acids include b2682 gene (ygaZ), b2683 gene (ygaH), b1242 gene (ychE), and b3434 gene (yhgN) (Japanese Patent Laid-Open No. 2002-300874) .

In addition, examples of a method for imparting or enhancing L-amino acid producing ability include a method for modifying bacteria so that the activity of a protein involved in sugar metabolism or a protein involved in energy metabolism is increased.

Proteins involved in sugar metabolism include proteins involved in sugar uptake and glycolytic enzymes. Genes encoding proteins involved in sugar metabolism include glucose 6-phosphate isomerase gene (pgi; WO 01/02542 pamphlet), pyruvate carboxylase gene (pyc; WO 99/18228 pamphlet, European application Publication 1092776), phosphoglucomutase gene (pgm; International Publication No. 03/04598 pamphlet), fructose diphosphate aldolase gene (pfkB, kfbp; International Publication No. 03/04664 pamphlet), transaldolase gene (talB; International (Publication 03/008611 pamphlet), fumarase gene (fum; international publication 01/02545 pamphlet), non-PTS sucrose uptake gene (csc; European application publication 149911 pamphlet), sucrose utilization gene (scrAB operon; international publication) No. 90/04636 pamphlet).

Examples of genes encoding proteins involved in energy metabolism include a transhydrogenase gene (pntAB; US Pat. No. 5,830,716), a cytochrome bo type oxidase (cyoB; European Patent Application Publication No. 1070376) Is mentioned.

The gene used for breeding the above-mentioned L-amino acid-producing bacteria is not limited to the above-exemplified genes or genes having a known base sequence, as long as it encodes a protein having the original function maintained. There may be. For example, a gene used for breeding an L-amino acid-producing bacterium is an amino acid in which one or several amino acids at one or several positions are substituted, deleted, inserted or added in the amino acid sequence of a known protein. It may be a gene encoding a protein having a sequence. Regarding gene and protein variants, the descriptions of aconitase and acetaldehyde dehydrogenase described below and conservative variants of genes encoding them can be applied mutatis mutandis.

<1-2> Enhancement of aconitase activity and acetaldehyde dehydrogenase activity The bacterium of the present invention has been modified to increase aconitase activity or to increase aconitase activity and acetaldehyde dehydrogenase activity. By modifying the bacterium to increase aconitase activity or to increase aconitase activity and acetaldehyde dehydrogenase activity, L-amino acid production by the bacterium when ethanol is used as a carbon source can be improved.

The bacterium of the present invention can be obtained by modifying a bacterium having an L-amino acid-producing ability so that the aconitase activity is increased or the aconitase activity and the acetaldehyde dehydrogenase activity are increased. The bacterium of the present invention can also be obtained by imparting or enhancing the ability to produce L-amino acid after modifying the bacterium so that aconitase activity is increased or aconitase activity and acetaldehyde dehydrogenase activity are increased. Can do. In addition, the bacterium of the present invention may have acquired L-amino acid-producing ability by being modified so that aconitase activity is increased or aconitase activity and acetaldehyde dehydrogenase activity are increased. The modification for constructing the bacterium of the present invention can be performed in any order.

“Aconitase” refers to a protein having an activity of reversibly catalyzing the isomerization reaction between citric acid and isocitrate (EC 4.2.1.3). This activity is also referred to as “aconitase activity”. A gene encoding aconitase is also referred to as “aconitase gene”. Aconitase activity can be measured, for example, by measuring the production of cis-aconitic acid from isocitrate (Gruer MJ, Guest JR., Microbiology., 1994, Oct; 140 (10): 2531-41.).

Examples of aconitase include AcnA protein encoded by acnA gene and AcnB protein encoded by acnB gene. In the present invention, for example, the activity of the AcnA protein may be enhanced, the activity of the AcnB protein may be enhanced, or the activities of both the AcnA protein and the AcnB protein may be enhanced. When the bacterium of the present invention is not modified so that the activity of acetaldehyde dehydrogenase is increased, at least the activity of AcnB protein is enhanced.

Examples of AcnA protein and AcnB protein include Escherichia coli, Pantoea ananatis, Pectobacterium atrosepticum (former name Erwinia カロ carotovora), Examples include AcnA protein and AcnB protein of bacteria belonging to the family Enterobacteriaceae such as Salmonella enterica.

The acnA gene of Escherichia coli K12-MG1655 strain corresponds to the sequence from positions 1335831 to 1338506 in the genome sequence registered as GenBank accession NC_000913 (VERSION NC_000913.3 GI: 556503834) in the NCBI database. The AcnA protein of MG1655 strain is registered as GenBank accession NP_415792 (version NP_415792.1 GI: 16129237). The nucleotide sequence of the acnA gene of MG1655 strain and the amino acid sequence of AcnA protein are shown in SEQ ID NOs: 21 and 22, respectively.

The acnA gene of the Pantoea ananatis AJ13355 strain corresponds to the complementary sequence of the sequences 1665661 to 1668362 in the genome sequence registered as GenBank accession NC_017531 (VERSION NC_017531.1GI: 386014600) in the NCBI database. The AcnA protein of AJ13355 strain is registered as GenBank accession YP_005934253 (version YP_005934253.1 GI: 386015968). The nucleotide sequence of the acnA gene of AJ13355 strain and the amino acid sequence of AcnA protein are shown in SEQ ID NOs: 23 and 24, respectively.

The acnA gene of the Pectobacterium atrosepticum SCRI1043 strain corresponds to the 2198282 to 2200954 position in the genome sequence registered as GenBank accession NC_004547 (VERSION NC_004547.2 GI: 50119055) in the NCBI database. In addition, the AcnA protein of SCRI1043 strain is registered as GenBank accession YP_050038 (version YP_050038.1 GI: 50120871). The nucleotide sequence of the acnA gene of SCRI1043 strain and the amino acid sequence of AcnA protein are shown in SEQ ID NOs: 25 and 26, respectively.

The acnA gene of Salmonella enterica serovar Typhi CT18 strain corresponds to the sequence from 1298278 to 1300953 in the genome sequence registered as GenBank accession NC_003198 (VERSION NC_003198.1 GI: 16762629) in the NCBI database. In addition, the CT18 strain AcnA protein is registered as GenBank accession NP_455785 (version NP_455785.1 GI: 16760168). The nucleotide sequence of the acnA gene of CT18 strain and the amino acid sequence of AcnA protein are shown in SEQ ID NOs: 27 and 28, respectively.

The acnB gene of Escherichia coli K12-MG1655 strain corresponds to the 131615-134212 positions in the genome sequence registered as GenBank accession NC_000913 (VERSION NC_000913.3 GI: 556503834) in the NCBI database. The AcnB protein of the MG1655 strain is registered as GenBank accession NP_414660 (version NP_414660.1 GI: 16128111). The nucleotide sequence of the acnB gene of the MG1655 strain and the amino acid sequence of the AcnB protein are shown in SEQ ID NOs: 29 and 30, respectively.

The acnB gene of Pantoea ananatis AJ13355 strain corresponds to the sequence of 116856 to 119552 in the genome sequence registered as GenBank accession NC_017531 (VERSION NC_017531.1GI: 386014600) in the NCBI database. The AcnB protein of the AJ13355 strain is registered as GenBank accession YP_005932972 (version YP_005932972.1 GI: 386014695). The nucleotide sequence of the acnB gene of AJ13355 strain and the amino acid sequence of AcnB protein are shown in SEQ ID NOs: 31 and 32, respectively.

The acnB gene of the Pectobacterium atrosepticum SCRI1043 strain corresponds to a complementary sequence of positions 4218908 to 4221505 in the genome sequence registered as GenBank accession NC_004547 (VERSION NC_004547.2 GI: 50119055) in the NCBI database. The AcnB protein of SCRI1043 strain is registered as GenBank accession YP_051867 (version YP_051867.1 GI: 50122700). The nucleotide sequence of the acnB gene of SCRI1043 strain and the amino acid sequence of AcnB protein are shown in SEQ ID NOs: 33 and 34, respectively.

The acnB gene of Salmonella enterica serovar Typhi CT18 strain corresponds to the 189006-191603 sequence in the genome sequence registered as GenBank accession NC_003198 (VERSION NC_003198.1 GI: 16762629) in the NCBI database. The CT18 strain AcnB protein is registered as GenBank accession NP_454772 (version NP_454772.1 GI: 16759155). The nucleotide sequence of the acnB gene of CT18 strain and the amino acid sequence of AcnB protein are shown in SEQ ID NOs: 35 and 36, respectively.

“Acetaldehyde dehydrogenase” is a protein (EC 1.2.1.3, EC 1.2.1.4, EC 1.2.) That reversibly catalyzes the reaction of producing acetic acid from acetaldehyde using NAD ⁺ or NADP ⁺ as an electron acceptor. 1.5, EC 1.2.1.22, etc.). This activity is also referred to as “acetaldehyde dehydrogenase activity”. A gene encoding acetaldehyde dehydrogenase is also referred to as “acetaldehyde dehydrogenase gene”. Acetaldehyde dehydrogenase activity can be measured, for example, by measuring acetaldehyde dehydride-dependent reduction of NAD ⁺ or NADP ⁺ (Ho KK, Weiner H., J. Bacteriol., 2005, Feb; 187 (3): 1067 -73.)

Acetaldehyde dehydrogenase is also referred to as “CoA-independent acetaldehyde dehydrogenase” and is distinguished from CoA-dependent acetaldehyde dehydrogenase (described later). In addition, acetaldehyde dehydrogenase is sometimes called “aldehyde dehydrogenase” or “lactoaldehyde dehydrogenase”.

Examples of acetaldehyde dehydrogenase include AldB protein encoded by aldB gene. Examples of the AldB protein include Escherichia coli, Pantoea ananatis, Pectobacterium atrosepticum (former name Erwinia carotovora), Salmonella enterica Examples include AldB protein of bacteria belonging to the family Enterobacteriaceae such as (Salmonella ica enterica).

The aldb gene of Escherichia coli K12-MG1655 strain corresponds to the complementary sequence of the sequence from 3749773 to 3756511 in the genome sequence registered as GenBank accession NC_000913 (VERSION NC_000913.3 GI: 556503834) in the NCBI database. The AldB protein of the MG1655 strain is registered as GenBank accession NP_418045 (version NP_418045.4 GI: 90111619). The nucleotide sequence of aldB gene of MG1655 strain and the amino acid sequence of AldB protein are shown in SEQ ID NOs: 37 and 38, respectively.

AldB gene homologue of Pantoea ananatis LMG20103 strain is registered as one of the aldA genes on the database. In the present invention, the aldb gene homolog is treated as an aldb gene. The aldb gene of Pantoea ananatis LMG 20103 strain corresponds to a complementary sequence of positions 2168098 to 2169570 in the genome sequence registered as GenBank accession NC_013956 (VERSION NC_013956.2 GI: 332139403) in the NCBI database. The AldB protein of LMG 20103 strain is registered as GenBank accession YP_003520235 (version YP_003520235.1 GI: 291617493). The nucleotide sequence of the aldB gene of LMGdB20103 strain and the amino acid sequence of the AldB protein are shown in SEQ ID NOs: 39 and 40, respectively.

The aldb gene of the Pectobacterium atrosepticum SCRI1043 strain corresponds to the 111626 to 113161 positions in the genome sequence registered as GenBank accession NC_004547 (VERSION NC_004547.2 GI: 50119055) in the NCBI database. In addition, the AldB protein of SCRI1043 strain is registered as GenBank accession YP_048222 (version YP_048222.1 GI: 50119055). The nucleotide sequence of the aldB gene of SCRI1043 strain and the amino acid sequence of AldB protein are shown in SEQ ID NOs: 41 and 42, respectively.

The aldB gene of Salmonella enterica serovar Typhi CT18 strain corresponds to the sequence of positions 3978586 to 3980124 in the genome sequence registered as GenBank accession NC_003198 (VERSION NC_003198.1 GI: 16762629) in the NCBI database. The AldB protein of CT18 strain is registered as GenBank accession NP_458246 (version NP_458246.1 GI: 16762629). The nucleotide sequence of the aldb gene of CT18 strain and the amino acid sequence of AldB protein are shown in SEQ ID NOs: 43 and 44, respectively.

The alignment results of these AldB proteins are shown in FIGS. The amino acid sequence homology between the AldB protein of Escherichiaichicoli K12 MG1655 and the AldB protein of Pantoea ananatis LMG 20103, Pectobacteriumtoatrosepticum SCRI1043, and Salmonella enterica serovar Typhi CT18 is 64.7%, 5.8%, and 81.4%, respectively. %.

That is, the aconitase gene may be a gene having the base sequence shown in SEQ ID NO: 21, 23, 25, 27, 29, 31, 33, or 35, for example. In addition, the aconitase may be a protein having an amino acid sequence shown in 22, 24, 26, 28, 30, 32, 34, or 36, for example. Further, the acetaldehyde dehydrogenase gene may be a gene having the base sequence shown in SEQ ID NO: 37, 39, 41, or 43, for example. The acetaldehyde dehydrogenase may be a protein having an amino acid sequence shown in 38, 40, 42, or 44, for example. In addition, the expression “having an (amino acid or base) sequence” includes the case of “including the (amino acid or base) sequence” and the case of “consisting of the (amino acid or base) sequence”.

As long as the original function is maintained, the aconitase may be a variant of the above exemplified aconitase, for example, the above exemplified AcnA protein or AcnB protein. Similarly, the aconitase gene may be a variant of the aconitase gene exemplified above, for example, the acnA gene or the acnB gene exemplified above as long as the original function is maintained. Further, the acetaldehyde dehydrogenase may be a variant of the above-exemplified acetaldehyde dehydrogenase, for example, the above-illustrated AldB protein, as long as the original function is maintained. Similarly, as long as the original function is maintained, the acetaldehyde dehydrogenase gene may be a variant of the acetaldehyde dehydrogenase gene exemplified above, for example, the aldb gene exemplified above. Such a variant in which the original function is maintained may be referred to as a “conservative variant”. Conservative variants include, for example, the above-exemplified aconitase and acetaldehyde dehydrogenase, and homologues and artificial modifications of genes encoding them.

In addition, the terms “AcnA protein”, “AcnB protein”, and “AldB protein” include conservative variants thereof in addition to the AcnA protein, AcnB protein, and AldB protein exemplified above, respectively. . Similarly, the terms “acnA gene”, “acnB gene”, and “aldB gene” are intended to include conservative variants thereof in addition to the acnA gene, acnB gene, and aldB gene respectively exemplified above. To do.

“The original function is maintained” means that the variant of the gene or protein has a function (activity or property) corresponding to the function (activity or property) of the original gene or protein. That is, “the original function is maintained” means that, in aconitase, a protein variant has aconitase activity, and in acetaldehyde dehydrogenase, a protein variant has acetaldehyde dehydrogenase activity. Say. In addition, in the case of an aconitase gene, “the original function is maintained” means that a variant of the gene encodes a protein in which the original function is maintained (that is, a protein having an aconitase activity). In the case of a dehydrogenase gene, it means that a variant of the gene encodes a protein whose original function is maintained (that is, a protein having acetaldehyde dehydrogenase activity).

The following are examples of conservative variants.

Examples of homologs of aconitase or acetaldehyde dehydrogenase include proteins obtained from public databases by BLAST search or FASTA search using the amino acid sequence as a query sequence. Moreover, the homologue of the aconitase gene or the acetaldehyde dehydrogenase gene can be obtained, for example, by PCR using the chromosomes of various microorganisms as templates and oligonucleotides prepared based on the above base sequences as primers.

An aconitase or acetaldehyde dehydrogenase may be used as long as the original function is maintained (for example, the amino acid sequence shown in SEQ ID NO: 22, 24, 26, 28, 30, 32, 34, or 36 for aconitase, acetaldehyde dehydrogenase). A protein having an amino acid sequence in which one or several amino acids at one or several positions are substituted, deleted, inserted or added in the amino acid sequence shown in SEQ ID NO: 38, 40, 42, or 44) Also good. The above “one or several” varies depending on the position and type of the amino acid residue in the three-dimensional structure of the protein, but specifically, for example, 1 to 50, 1 to 40, 1 to 30, Preferably, it means 1-20, more preferably 1-10, even more preferably 1-5, particularly preferably 1-3.

The substitution, deletion, insertion, or addition of one or several amino acids described above is a conservative mutation that maintains the protein function normally. A typical conservative mutation is a conservative substitution. Conservative substitution is a polar amino acid between Phe, Trp, and Tyr when the substitution site is an aromatic amino acid, and between Leu, Ile, and Val when the substitution site is a hydrophobic amino acid. In this case, between Gln and Asn, when it is a basic amino acid, between Lys, Arg, and His, when it is an acidic amino acid, between Asp and Glu, when it is an amino acid having a hydroxyl group Is a mutation that substitutes between Ser and Thr. Specifically, substitutions considered as conservative substitutions include substitution from Ala to Ser or Thr, substitution from Arg to Gln, His or Lys, substitution from Asn to Glu, Gln, Lys, His or Asp, Asp to Asn, Glu or Gln, Cys to Ser or Ala, Gln to Asn, Glu, Lys, His, Asp or Arg, Glu to Gly, Asn, Gln, Lys or Asp Substitution, Gly to Pro substitution, His to Asn, Lys, Gln, Arg or Tyr substitution, Ile to Leu, Met, Val or Phe substitution, Leu to Ile, Met, Val or Phe substitution, Substitution from Lys to Asn, Glu, Gln, His or Arg, substitution from Met to Ile, Leu, Val or Phe, substitution from Phe to Trp, Tyr, Met, Ile or Leu, Ser to Thr or Ala Substitution, substitution from Thr to Ser or Ala, substitution from Trp to Phe or Tyr, substitution from Tyr to His, Phe or Trp, and substitution from Val to Met, Ile or Leu. In addition, amino acid substitutions, deletions, insertions, additions, or inversions as described above include naturally occurring mutations (mutants or variants) such as those based on individual differences or species differences in the organism from which the protein is derived. Also included by

Further, as long as the original function is maintained, aconitase or acetaldehyde dehydrogenase is 80% or more, preferably 90% or more, more preferably 95% or more, still more preferably 97% or more, based on the entire amino acid sequence. Particularly preferably, it may be a protein having an amino acid sequence having a homology of 99% or more. In the present specification, “homology” may refer to “identity”.

In addition, as long as the original function is maintained, aconitase or acetaldehyde dehydrogenase is the above base sequence (for example, the base sequence shown in SEQ ID NO: 21, 23, 25, 27, 29, 31, 33, or 35 for aconitase, acetaldehyde). Encoded by a DNA that hybridizes under stringent conditions with a probe that can be prepared from the base sequence shown in SEQ ID NO: 37, 39, 41, or 43 for dehydrogenase, for example, a complementary sequence to all or part of the base sequence. May be a protein. Such a probe can be prepared, for example, by PCR using an oligonucleotide prepared based on the base sequence as a primer and a DNA fragment containing the base sequence as a template. “Stringent conditions” refers to conditions under which so-called specific hybrids are formed and non-specific hybrids are not formed. For example, highly homologous DNAs, for example, 80% or more, preferably 90% or more, more preferably 95% or more, further preferably 97% or more, particularly preferably 99% or more. Are hybridized and DNAs with lower homology do not hybridize with each other, or normal Southern hybridization washing conditions of 60 ° C., 1 × SSC, 0.1% SDS, preferably 60 ° C., 0.1 × SSC And 0.1% SDS, more preferably 68 ° C., 0.1 × SSC, at a salt concentration and temperature corresponding to 0.1% SDS, conditions of washing once, preferably 2 to 3 times. For example, when a DNA fragment having a length of about 300 bp is used as a probe, hybridization washing conditions include 50 ° C., 2 × SSC, 0.1% SDS.

The percentage sequence identity between two sequences can be determined using, for example, a mathematical algorithm. Non-limiting examples of such mathematical algorithms include Myers and Miller (1988) CABIOS 4: 11 17 algorithm, Smith et aldv (1981) Adv. Appl. Math. 2: 482 local homology algorithm, Needleman and Wunsch (1970) J. Mol. Biol. 48: 443 453 homology alignment algorithm, Pearson and Lipman (1988) Proc. Natl. Acad. Sci. 85: 2444 2448 similarity search method, Karlin and Altschul 類似 (1993) Proc. Natl. Acad. Sci. USA 90: 5873 5877, an improved algorithm of Karlin and Altschul (1990) Proc. Natl. Acad. Sci. USA 872264.

Using a program based on these mathematical algorithms, sequence comparison (alignment) for determining sequence identity can be performed. The program can be appropriately executed by a computer. Such programs include, but are not limited to, PC / Gene program CLUSTAL (available from Intelligents, Mountain View, Calif.), ALIGN program (Version 2.0), and Wisconsin Genetics Software Package, Version 8 (Genetics Computer Group (GCG), 575 Science Drive, available from Madison, Wis., USA) GAP, BESTFIT, BLAST, FASTA, and TFASTA. Alignment using these programs can be performed using initial parameters, for example. Regarding the CLUSTAL program, Higgins et al. (1988) Gene 73: 237 244 (1988), Higgins et al. (1989) CABIOS 5: 151 153, Corpet et al. (1988) Nucleic Acids Res. 16: 10881 90, Huang et al. (1992) CABIOS 8: 155 65 and Pearson et al. (1994) Meth. Mol. Biol. 24: 307 331.

In order to obtain a nucleotide sequence having homology with the nucleotide sequence encoding the protein of interest, specifically, for example, a BLAST nucleotide search can be performed with the BLASTN program, score = 100, word length = 12. In order to obtain an amino acid sequence having homology with the protein of interest, specifically, for example, a BLAST protein search can be performed with the BLASTX program, score = 50, word length = 3. Please refer to http://www.ncbi.nlm.nih.gov for BLAST nucleotide search and BLAST protein search. In addition, Gapped BLAST (BLAST 2.0) can be used to obtain an alignment with a gap added for comparison purposes. In addition, PSI-BLAST (BLAST 2.0) can be used to perform an iterated search that detects distant relationships between sequences. For Gapped BLAST and PSI-BLAST, see Altschul et al. (1997) Nucleic Acids Res. 25: 3389. When utilizing BLAST, Gapped BLAST, or PSI-BLAST, for example, the initial parameters of each program (eg, BLASTN for nucleotide sequences, BLASTX for amino acid sequences) can be used. The alignment may be performed manually.

The sequence identity between two sequences is calculated as the ratio of residues that match between the two sequences when the two sequences are aligned for maximum matching.

The aconitase gene or acetaldehyde dehydrogenase gene may be one obtained by substituting an arbitrary codon with an equivalent codon as long as the original function is maintained. For example, the aconitase gene or the acetaldehyde dehydrogenase gene may be modified to have an optimal codon depending on the codon usage frequency of the host to be used.

In addition, the description regarding the above-mentioned conservative variants of genes and proteins can be applied mutatis mutandis to arbitrary proteins such as L-amino acid biosynthetic enzymes and ethanol metabolizing enzymes, and genes encoding them.

<1-3> Ethanol assimilation The bacterium of the present invention has ethanol assimilation. “Having ethanol assimilation” means being able to grow in a minimal medium containing ethanol as the sole carbon source. The bacterium of the present invention may inherently have ethanol-assimilating properties, or may be modified to have ethanol-assimilating properties. Bacteria having ethanol-assimilating properties can be obtained, for example, by imparting ethanol-assimilating properties to the bacteria as described above, or by enhancing the ethanol-assimilating properties of bacteria as described above.

Ethanol assimilation can be imparted or enhanced by modifying bacteria so that the activity of one or more enzymes selected from ethanol metabolizing enzymes is increased. That is, the bacterium of the present invention may be modified to increase the activity of one or more enzymes selected from ethanol metabolizing enzymes.

Examples of the ethanol metabolism enzyme include alcohol dehydrogenase and CoA-dependent acetaldehyde dehydrogenase.

“Alcohol dehydrogenase” means a protein (EC 1.1.1.1, EC 1.1.1.2, EC 1.1.1.71) that has an activity of reversibly catalyzing a reaction for producing acetaldehyde from ethanol using NAD ⁺ or NADP ⁺ as an electron acceptor. Etc.). This activity is also referred to as “alcohol dehydrogenase activity”. Alcohol dehydrogenase activity can be measured, for example, by measuring ethanol-dependent reduction of NAD ⁺ (Clark D, Cronan JE Jr., J Bacteriol., 1980, Jan; 141 (1): 177-83.) .

“CoA-dependent acetaldehyde dehydrogenase” refers to a protein (EC 1.2.1.10) having an activity of reversibly catalyzing the reaction of producing acetyl CoA from acetaldehyde using NAD ⁺ or NADP ⁺ as an electron acceptor. This activity is also referred to as “CoA-dependent acetaldehyde dehydrogenase activity”. CoA-dependent acetaldehyde dehydrogenase activity can be measured, for example, by measuring acetaldehyde hydride and CoA-dependent reduction of NAD ⁺ (Rudolph FB, Purich DL, Fromm HJ., J Biol Chem., 1968, Nov 10; 243 (21): 5539-45.).

Examples of ethanol metabolic enzymes include AdhE protein encoded by adhE gene. The AdhE protein is a bifunctional enzyme and has both alcohol dehydrogenase activity and CoA-dependent acetaldehyde dehydrogenase activity. Examples of the AdhE protein include Escherichia coli, Pantoea ananatis, Pectobacterium atrosepticum (former name: Erwinia carotovora), Salmonella en AdhE protein of bacteria belonging to the family Enterobacteriaceae such as (Salmonella enterica).

The adhE gene of Escherichia coli K12-MG1655 strain corresponds to a complementary sequence of positions 1295446 to 1298121 in the genome sequence registered as GenBank accession NC_000913 (VERSION NC_000913.3 GI: 556503834) in the NCBI database. The AdhE protein of MG1655 strain is registered as GenBank accession NP_415757 (version NP_415757.1 GI: 16129202). The nucleotide sequence of the adhE gene of the MG1655 strain and the amino acid sequence of the AdhE protein are shown in SEQ ID NOs: 45 and 46, respectively.

The adhE gene of Pantoea ananatis LMG 20103 strain corresponds to the sequence from 2335387 to 2233807 in the genome sequence registered as GenBank accession NC_013956 (VERSION NC_013956.2 GI: 332139403) in the NCBI database. The AdhE protein of LMG 20103 strain is registered as GenBank accession YP_003520384 (version YP_003520384.1 GI: 291617642). The nucleotide sequence of the adhE gene of LMGdh20103 strain and the amino acid sequence of the AdhE protein are shown in SEQ ID NOs: 47 and 48, respectively.

The adhE gene of the Pectobacterium atrosepticum SCRI1043 strain corresponds to the sequence of 2634501-2637176 in the genome sequence registered as GenBank accession NC_004547 (VERSION NC_004547.2 GI: 50119055) in the NCBI database. The AdhE protein of the SCRI1043 strain is registered as GenBank accession YP_050421 (version YP_050421.1 GI: 50121254). The nucleotide sequence of the adhE gene of SCRI1043 strain and the amino acid sequence of the AdhE protein are shown in SEQ ID NOs: 49 and 50, respectively.

The adhE gene homologue of Salmonella enterica serovar Typhi CT18 strain is registered as an adh gene in the database. In the present invention, the adhE gene homolog is treated as an adhE gene. The adhE gene of Salmonella enterica serovar Typhi CT18 strain corresponds to a complementary sequence of sequences 1259893 to 1262571 in the genome sequence registered as GenBank accession NC_003198 (VERSION NC_003198.1 GI: 16762629) in the NCBI database. The CT18 strain AdhE protein is registered as GenBank accession NP_455751 (version NP_455751.1 GI: 16760134). The nucleotide sequence of the adhE gene of CT18 strain and the amino acid sequence of the AdhE protein are shown in SEQ ID NOs: 51 and 52, respectively.

The alignment results of these AdhE proteins are shown in FIGS. The amino acid sequence homology between the AdhE protein of Escherichia coli K12 MG1655 strain and the AdhE protein of Pantoea ananatis LMG 20103 strain, Pectobacterium atrosepticum SCRI1043 strain and Salmonella enterica serovar Typhi CT18 strain is 89.0%, 99.1 %.

The ethanol-metabolizing enzyme may be a conservative variant of the above-exemplified ethanol-metabolizing enzyme, for example, the AdhE protein of bacteria belonging to the Enterobacteriaceae family exemplified above. For example, the AdhE protein is a protein having an amino acid sequence in which one or several amino acids at one or several positions are substituted, deleted, inserted or added in the amino acid sequence shown in 46, 48, 50, or 52 It may be. Regarding the gene and protein variants, the above descriptions concerning aconitase and acetaldehyde dehydrogenase and conservative variants of the genes encoding them can be applied mutatis mutandis.

It is preferable that the bacterium of the present invention has ethanol assimilation property under aerobic conditions (ethanol can be assimilated aerobically). “Having ethanol assimilation under aerobic conditions” means being able to grow under aerobic conditions in a minimal medium with ethanol as the sole carbon source. In addition, “having ethanol assimilation under aerobic conditions” means, for example, the specific activity of alcohol dehydrogenase in a cell-free extract prepared from cells obtained by aerobic culture of the bacterium of the present invention. For example, it may be 1.5 μU / mg protein or more, preferably 5 μU / mg protein or more, more preferably 10 μU / mg protein or more. In addition, 1 ナーゼ U alcohol dehydrogenase activity is 1 nmol NADH per minute under the above activity measurement conditions (Clark D, Cronan JE Jr., J Bacteriol., 1980, Jan; 141 (1): 177-83.). Is defined as the activity that produces “Aerobic conditions” refers to culture conditions in which oxygen is supplied to the culture system by oxygen supply means such as aeration, shaking, and stirring. The bacterium of the present invention may inherently have ethanol assimilation under aerobic conditions or may be modified to have ethanol assimilation under aerobic conditions. For example, Escherichia coli cannot generally assimilate ethanol aerobically, but Escherichia coli may be modified and used as a bacterium of the present invention so that ethanol can be assimilated aerobically.

Ethanol assimilation under aerobic conditions can be imparted or enhanced by modifying bacteria so that the activity under aerobic conditions of one or more enzymes selected from ethanol metabolizing enzymes is increased. That is, the bacterium of the present invention may be modified so that the activity under aerobic conditions of one or more enzymes selected from ethanol metabolizing enzymes is increased.

Ethanol assimilation under aerobic conditions can be imparted or enhanced, for example, by modifying the bacterium to retain the adhE gene expressed under the control of a promoter that functions under aerobic conditions.

Such modification can be achieved, for example, by replacing the original promoter of the adhE gene on the bacterial genome with a promoter that functions under aerobic conditions. Alternatively, the adhE gene may be bound downstream of a promoter that functions under aerobic conditions and introduced into bacteria, or the adhE gene may be introduced downstream of a promoter that functions under aerobic conditions on the bacterial genome. Regarding the replacement of the promoter and the introduction of the gene, the description of the “method for increasing the protein activity” described later can be referred to.

The promoter that functions under aerobic conditions is not particularly limited as long as it can express the adhE gene under aerobic conditions to the extent that the bacterium of the present invention can assimilate ethanol. Promoters which function under aerobic conditions, for example, glycolysis, pentose phosphate pathway, TCA circuit, P ₁₄ promoter used in the promoter and examples of genes of amino acid biosynthesis (SEQ ID NO: 1). Examples of promoters that function under aerobic conditions include strong T7 promoter, trp promoter, lac promoter, thr promoter, tac promoter, trc promoter, tet promoter, araBAD promoter, rpoH promoter, PR promoter, and PL promoter. Also included are promoters.

Ethanol assimilation under aerobic conditions is conferred or enhanced, for example, by modifying the bacterium to retain the adhE gene encoding the AdhE protein with a mutation that improves resistance to inactivation under aerobic conditions it can. “Mutation that improves resistance to inactivation under aerobic conditions” is also referred to as “aerobic resistance mutation”.

AdhE protein having an aerobic tolerance mutation is also referred to as “mutant AdhE protein”. A gene encoding a mutant AdhE protein is also referred to as a “mutant adhE gene”.

AdhE protein that does not have an aerobic tolerance mutation is also referred to as “wild-type AdhE protein”. A gene encoding a wild type AdhE protein is also referred to as a “wild type adhE gene”. The “wild type” here is a description for convenience to distinguish it from the “mutant type”, and is not limited to those obtained naturally unless it has an aerobic tolerance mutation. Examples of the wild-type AdhE protein include the AdhE protein of bacteria belonging to the family Enterobacteriaceae exemplified above. Moreover, the conservative variants of the AdhE protein of the bacteria belonging to the family Enterobacteriaceae exemplified above are all wild-type AdhE proteins unless they have an aerobic tolerance mutation.

As the aerobic tolerance mutation, the amino acid residue corresponding to the glutamic acid residue at position 568 in the amino acid sequence of the wild type AdhE protein in the amino acid sequence shown in SEQ ID NO: 46 (the amino acid sequence of the wild type AdhE protein of Escherichia coli K12 MG1655 strain) is used. Examples include a mutation in which a group is substituted with an amino acid residue other than glutamic acid and aspartic acid (WO2008 / 010565). As amino acid residues after substitution, L (Lys), R (Arg), H (His), A (Ala), V (Val), L (Leu), I (Ile), G (Gly) S ( Ser), T (Thr), P (Pro), F (Phe), W (Trp), Y (Tyr), C (Cys), M (Met), N (Asn), Q (Gln) . The amino acid residue after substitution may be, for example, a lysine residue. The same mutation when the amino acid residue after substitution is a lysine residue is also referred to as “Glu568Lys” or “E568K”.

The mutant AdhE protein may further have the following additional mutations:
(A) A mutation in which the amino acid residue corresponding to the glutamic acid residue at position 560 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with another amino acid residue in the amino acid sequence of the wild-type AdhE protein;
(B) a mutation in which the amino acid residue corresponding to the phenylalanine residue at position 566 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with another amino acid residue in the amino acid sequence of the wild-type AdhE protein;
(C) In the amino acid sequence of the wild-type AdhE protein, the glutamic acid residue at position 22, the methionine residue at position 236, the tyrosine residue at position 461, the isoleucine residue at position 554, and 786 in the amino acid sequence shown in SEQ ID NO: 46 A mutation in which the amino acid residue corresponding to the alanine residue at the position is substituted with another amino acid residue;
(D) Combination of the above mutations.

In the above additional mutation, the substituted amino acid residues include L (Lys), R (Arg), H (His), A (Ala), V (Val), L (Leu), and I (Ile). , G (Gly) S (Ser), T (Thr), P (Pro), F (Phe), W (Trp), Y (Tyr), C (Cys), M (Met), D (Asp), Among E (Glu), N (Asn), and Q (Gln), those other than the original amino acid residue can be mentioned. In the mutation (A), the amino acid residue after substitution may be, for example, a lysine residue. In the mutation (B), the amino acid residue after substitution may be, for example, a valine residue. In the mutation (C), the substituted amino acid residues are, for example, glycine residue (Glu22Gly) at position 22, valine residue (Met236Val) at position 236, cysteine residue (Tyr461Cys) at position 461, and position 554. It may be a serine residue (Ile554Ser) and a valine residue (Ala786Val) for position 786.

In the amino acid sequence of any wild-type AdhE protein, “the amino acid residue corresponding to the amino acid residue at position n in the amino acid sequence shown in SEQ ID NO: 46” refers to the amino acid sequence of the target wild-type AdhE protein and SEQ ID NO: 46 It means an amino acid residue corresponding to the amino acid residue at position n in the amino acid sequence shown in SEQ ID NO: 46 in the alignment with the amino acid sequence. That is, in the above mutation, the position of the amino acid residue does not necessarily indicate an absolute position in the amino acid sequence of the wild type AdhE protein, but indicates a relative position based on the amino acid sequence described in SEQ ID NO: 46. is there. For example, in the wild-type AdhE protein consisting of the amino acid sequence shown in SEQ ID NO: 46, when one amino acid residue is deleted at the N-terminal position from the n-position, the original n-position amino acid residue is counted from the N-terminal. The amino acid residue at the (n-1) th position is regarded as “the amino acid residue corresponding to the amino acid residue at position n in the amino acid sequence shown in SEQ ID NO: 46”. Similarly, for example, when the amino acid residue at position 567 in the amino acid sequence of an AdhE protein homologue of a certain microorganism corresponds to position 568 in the amino acid sequence shown in SEQ ID NO: 46, the amino acid residue is the AdhE protein. This is the “amino acid residue corresponding to the amino acid residue at position 568 in the amino acid sequence shown in SEQ ID NO: 46” in the homologue.

Alignment can be performed using, for example, known gene analysis software. Specific gene analysis software includes DNA Solutions from Hitachi Solutions, GENETYX from GENETICS, and ClustalW published by DDBJ (Elizabeth C. Tyler et al., Computers and Biomedical Research, 24 (1), 72-96, 1991; Barton GJ et al., Journal of molecular biology, 198 (2), 327-37. 1987; Thompson JD et al., Nucleic acid Reseach, 22 (22), 4673-80. 1994).

The mutant adhE gene can be obtained, for example, by modifying the wild-type adhE gene so that the encoded AdhE protein has an aerobic tolerance mutation. The wild-type adhE gene to be modified can be obtained, for example, by cloning from an organism having the wild-type adhE gene or by chemical synthesis. In addition, the mutant adhE gene may be obtained directly by, for example, chemical synthesis.

The gene can be modified by a known method. For example, a target mutation can be introduced into a target site of DNA by site-specific mutagenesis. As site-directed mutagenesis, a method using PCR (Higuchi, R., 61, in PCR technology, rlErlich, H. A. Eds., Stockton press (1989); Carter, P., ethMeth. In Enzymol., 154, 382 (1987)) and methods using phage (Kramer, W. and Frits, H. J., Meth. In Enzymol., 154, 350 (1987); Kunkel, T. A. et al., Meth In Enzymol., 154, 367 (1987)).

The mutant adhE gene is introduced into the bacterium of the present invention so that it can be expressed. Specifically, the gene can be introduced into the bacterium of the present invention so as to be expressed under the control of a promoter that functions under aerobic conditions. For the introduction of the gene, reference can be made to the description in “Method of increasing protein activity” described later.

<1-4> Other Modifications In the bacterium of the present invention, the activity of pyruvate synthase (also referred to as “PS”) and / or pyruvate: NADP ⁺ oxidoreductase (also referred to as “PNO”) is increased. It may be modified (WO2009 / 031565).

“Pyruvate synthase” refers to an enzyme (EC 1.2.7.1) that reversibly catalyzes the reaction of producing pyruvate from acetyl-CoA and CO ₂ using reduced ferredoxin or reduced flavodoxin as an electron donor. PS is also referred to as pyruvate oxidoreductase, pyruvate ferredoxin oxidoreductase, or pyruvate flavodoxin oxidoreductase. The activity of PS can be measured, for example, according to the method of Yoon et al. (Yoon, K. S. et al. 1997. Arch. Microbiol. 167: 275-279).

PS-encoding genes (PS genes) include PS genes of bacteria having a reductive TCA cycle such as Chlorobium tepidum, Hydrogenobacter thermophilus, and enterobacteria such as Escherichia coli Autotrophic methane-producing archaea such as PS gene of bacteria belonging to the family, Methanococcus maripaludis, Methanococdocus janaschi (Methanocaldococcus jannaschii), Methanothermobacter thermautotrophicus, etc. methanogens) PS gene.

“Pyruvate: NADP ⁺ oxidoreductase” refers to an enzyme (EC 1.2.1.15) that reversibly catalyzes the reaction of generating pyruvate from acetyl-CoA and CO ₂ using NADPH or NADH as an electron donor. Pyruvate: NADP ⁺ oxidoreductase is also referred to as pyruvate dehydrogenase. The activity of PNO can be measured, for example, according to the method of Inui et al. (Inui, H. et al. 1987. J. Biol. Chem. 262: 9130-9135).

As a gene encoding PNO (PNO gene), a PNO gene (Nakazawa, M. される et al. 2000. FEBS Lett. 479: 155) of Euglena gracilis which is classified as a protozoan in a photosynthetic eukaryotic microorganism. -156; GenBank Accession No. AB021127), PNO gene of protozoan Cryptosporidium parvum (Rotte, C. et al. 2001. Mol. (Tharassiosira pseudonana) PNO homologous gene (Ctrnacta, V. et al. 2006. J. Eukaryot. Microbiol. 53: 225-231).

Enhancement of PS activity can be achieved by improving the supply of electron donors required for PS activity in addition to the method for increasing protein activity as described later. For example, PS activity can be enhanced by enhancing the activity of recycling ferredoxin or flavodoxin oxidized form to reduced form, enhancing the biosynthetic ability of ferredoxin or flavodoxin, or a combination thereof (WO2009 / 031565 ).

Examples of proteins having the activity of recycling ferredoxin or flavodoxin oxidized form to reduced form include ferredoxin-NADP ⁺ reductase. “Ferredoxin-NADP ⁺ reductase” refers to an enzyme (EC 1.18.1.2) that reversibly catalyzes a reaction of converting ferredoxin or an oxidized form of flavodoxin into a reduced form using NADPH as an electron donor. Ferredoxin-NADP ⁺ reductase is also referred to as flavodoxin-NADP ⁺ reductase. The activity of ferredoxin-NADP ⁺ reductase can be measured, for example, according to the method of Blaschkowski et al. (Blaschkowski, H. P. et al. 1982. Eur. J. Biochem. 123: 563-569).

The genes encoding ferredoxin-NADP ⁺ reductase (ferredoxin-NADP ⁺ reductase gene) include the fpr gene of Escherichia coli, the ferredoxin-NADP ⁺ reductase gene of Corynebacterium glutamicum, and the NADPH- of Pseedomonas putida. And putidaredoxin reductase gene (Koga, H. et al. 1989. J. Biochem. (Tokyo) 106: 831-836).

The biosynthetic ability of ferredoxin or flavodoxin can be enhanced by enhancing the expression of a gene encoding ferredoxin (ferredoxin gene) or a gene encoding flavodoxin (flavodoxin gene). The ferredoxin gene or flavodoxin gene is not particularly limited as long as it encodes ferredoxin or flavodoxin that can be used by PS and an electron donor regeneration system.

Examples of the ferredoxin gene include Escherichia coli fdx gene and yfhL gene, corynebacterium glutamicum fer gene, bacteria ferredoxin gene having a reductive TCA cycle such as Chlorobium tepidum and Hydrogenobacter thermophilus. Examples of the flavodoxin gene include Escherichia coli fldA gene and fldB gene, and bacterial flavodoxin gene having a reductive TCA cycle.

Moreover, the bacterium of the present invention may be modified so that the activity of ribonuclease G is reduced (Japanese Patent Laid-Open No. 2012-100537).

Further, the bacterium of the present invention may be modified so as to have a mutant ribosome S1 protein (JP 2013-074795).

Moreover, the bacterium of the present invention may be modified so that the concentration of intracellular hydrogen peroxide decreases (Japanese Patent Laid-Open No. 2014-036576).

In addition, the above genes, for example, PS gene, PNO gene, ferredoxin-NADP ⁺ reductase gene, ferredoxin gene, flavodoxin gene may be a gene having the above-described gene information or a known one as long as the function of the encoded protein is not impaired. It is not limited to a gene having a base sequence, and may be a variant thereof. For example, the gene is a gene encoding a protein having an amino acid sequence in which one or several amino acids at one or several positions are substituted, deleted, inserted or added in the amino acid sequence of a known protein. May be. Regarding the gene and protein variants, the above descriptions concerning aconitase and acetaldehyde dehydrogenase and conservative variants of the genes encoding them can be applied mutatis mutandis.

<1-5> Technique for Increasing Protein Activity A technique for increasing the activity of proteins such as aconitase and acetaldehyde dehydrogenase will be described below.

"" Protein activity increases "means that the activity per cell of the protein is increased relative to unmodified strains such as wild strains and parental strains. Note that “increasing protein activity” is also referred to as “enhancing protein activity”. “Protein activity increases” specifically means that the number of molecules per cell of the protein is increased and / or the function per molecule of the protein compared to an unmodified strain. Is increasing. That is, “activity” in the case of “increasing protein activity” means not only the catalytic activity of the protein, but also the transcription amount (mRNA amount) or translation amount (protein amount) of the gene encoding the protein. May be. “Protein activity increases” means not only to increase the activity of the protein in a strain that originally has the activity of the target protein, but also to the activity of the protein in a strain that does not originally have the activity of the target protein. Including granting. Further, as long as the activity of the protein increases as a result, the activity of the target protein inherent in the host may be reduced or eliminated, and the activity of a suitable target protein may be imparted.

The activity of the protein is not particularly limited as long as it is increased compared to the non-modified strain. For example, the protein activity is increased 1.5 times or more, 2 times or more, or 3 times or more compared to the non-modified strain. Good. In addition, when the non-modified strain does not have the activity of the target protein, it is sufficient that the protein is generated by introducing a gene encoding the protein. For example, the protein has an enzymatic activity. It may be produced to the extent that it can be measured.

Modification that increases the activity of the protein is achieved, for example, by increasing the expression of the gene encoding the protein. “Gene expression is increased” means that the expression level of the gene per cell is increased as compared to a non-modified strain such as a wild strain or a parent strain. “Gene expression increases” specifically means that the amount of gene transcription (mRNA amount) increases and / or the amount of gene translation (protein amount) increases. Good. Note that “increasing gene expression” is also referred to as “enhanced gene expression”. The expression of the gene may be increased 1.5 times or more, 2 times or more, or 3 times or more, for example, as compared to the unmodified strain. In addition, “increasing gene expression” means not only increasing the expression level of a target gene in a strain that originally expresses the target gene, but also in a strain that originally does not express the target gene. Including expressing a gene. That is, “increasing gene expression” includes, for example, introducing the gene into a strain that does not hold the target gene and expressing the gene.

An increase in gene expression can be achieved, for example, by increasing the copy number of the gene.

Increase in gene copy number can be achieved by introducing the gene into the host chromosome. Introduction of a gene into a chromosome can be performed, for example, using homologous recombination (Miller I, J. H. Experiments in Molecular Genetics, 1972, Cold Spring Harbor Laboratory). Examples of gene introduction methods using homologous recombination include the Red-driven integration method (Datsenko, K. A, and Wanner, B. L. Proc. Natl. Acad. Sci. U S A. 97). : 6640-6645 (2000)) and other methods using linear DNA, a method using a plasmid containing a temperature-sensitive replication origin, a method using a plasmid capable of conjugation transfer, and a suspension vector that does not have an origin of replication and functions in the host And a transduction method using a phage. Only one copy of the gene may be introduced, or two copies or more may be introduced. For example, multiple copies of a gene can be introduced into a chromosome by performing homologous recombination with a sequence having multiple copies on the chromosome as a target. Examples of sequences having many copies on a chromosome include repetitive DNA sequences (inverted DNA) and inverted repeats present at both ends of a transposon. Alternatively, homologous recombination may be performed by targeting an appropriate sequence on a chromosome such as a gene unnecessary for production of the target substance. The gene can also be randomly introduced onto the chromosome using transposon or Mini-Mu (Japanese Patent Laid-Open No. 2-109985, US Pat. No. 5,882,888, EP805867B1).

Confirmation of the introduction of the target gene on the chromosome was performed using Southern hybridization using a probe having a sequence complementary to all or part of the gene, or a primer prepared based on the sequence of the gene. It can be confirmed by PCR.

An increase in the copy number of a gene can also be achieved by introducing a vector containing the gene into a host. For example, a DNA fragment containing a target gene can be linked to a vector that functions in the host to construct an expression vector for the gene, and the host can be transformed with the expression vector to increase the copy number of the gene. it can. A DNA fragment containing a target gene can be obtained, for example, by PCR using a genomic DNA of a microorganism having the target gene as a template. As the vector, a vector capable of autonomous replication in a host cell can be used. Moreover, the vector may be equipped with a promoter or terminator for expressing the inserted gene. The vector is preferably a multicopy vector. In order to select a transformant, the vector preferably has a marker such as an antibiotic resistance gene. Moreover, the vector may be equipped with a promoter or terminator for expressing the inserted gene. The vector may be, for example, a vector derived from a bacterial plasmid, a vector derived from a yeast plasmid, a vector derived from a bacteriophage, a cosmid, or a phagemid. As vectors capable of autonomous replication in bacteria of the Enterobacteriaceae family such as Escherichia coli, specifically, for example, pUC19, pUC18, pHSG299, pHSG399, pHSG398, pBR322, pSTV29 (all available from Takara Bio Inc.), pACYC184, pMW219 (Nippon Gene), pTrc99A (Pharmacia), pPROK vector (Clontech), pKK233-2 (Clontech), pET vector (Novagen), pQE vector (Qiagen), pACYC vector A broad host range vector RSF1010.

When a gene is introduced, the gene only needs to be retained in the bacterium of the present invention so that it can be expressed. Specifically, the gene may be introduced so as to be expressed under the control of a promoter sequence that functions in the bacterium of the present invention. The promoter may be a host-derived promoter or a heterologous promoter. The promoter may be a native promoter of a gene to be introduced or a promoter of another gene. The promoter, for example, glycolysis, pentose phosphate pathway, TCA circuit, P ₁₄ promoter used in the promoter and examples of genes of amino acid biosynthesis (SEQ ID NO: 1). As the promoter, for example, a stronger promoter as described later may be used.

A transcription terminator can be placed downstream of the gene. The terminator is not particularly limited as long as it functions in the bacterium of the present invention. The terminator may be a host-derived terminator or a heterologous terminator. The terminator may be a terminator specific to the gene to be introduced, or may be a terminator of another gene. Specific examples of the terminator include T7 terminator, T4 terminator, fd phage terminator, tet terminator, and trpA terminator.

The vectors, promoters, and terminators that can be used in various microorganisms are described in detail in, for example, “Basic Course of Microbiology 8, Genetic Engineering, Kyoritsu Shuppan, 1987”, and these can be used.

In addition, when two or more genes are introduced, each gene may be retained in the bacterium of the present invention so that it can be expressed. For example, all the genes may be held on a single expression vector, or all may be held on a chromosome. Moreover, each gene may be separately hold | maintained on several expression vector, and may be separately hold | maintained on the single or several expression vector and chromosome. Further, an operon may be constructed by introducing two or more genes. “When two or more genes are introduced” means, for example, when a gene encoding each of two or more enzymes is introduced, each of two or more subunits constituting a single enzyme is encoded. And a combination thereof.

The gene to be introduced is not particularly limited as long as it encodes a protein that functions in the host. The introduced gene may be a host-derived gene or a heterologous gene. The gene to be introduced can be obtained by PCR using, for example, a primer designed based on the base sequence of the gene, and using a genomic DNA of an organism having the gene or a plasmid carrying the gene as a template. The introduced gene may be totally synthesized based on the base sequence of the same gene (Gene, 60 (1), 115-127 (1987)). The acquired gene can be used as it is or after being appropriately modified.

When the protein functions as a complex composed of a plurality of subunits, all of the plurality of subunits may be modified or only a part may be modified as long as the activity of the protein increases as a result. . That is, for example, when the activity of a protein is increased by increasing the expression of a gene, the expression of a plurality of genes encoding those subunits may be enhanced, or only a part of the expression may be enhanced. Also good. Usually, it is preferable to enhance the expression of all of a plurality of genes encoding these subunits. In addition, each subunit constituting the complex may be derived from one organism or two or more different organisms as long as the complex has the function of the target protein. That is, for example, genes derived from the same organism encoding a plurality of subunits may be introduced into the host, or genes derived from different organisms may be introduced into the host.

Moreover, the increase in gene expression can be achieved by improving the transcription efficiency of the gene. Moreover, the increase in gene expression can be achieved by improving the translation efficiency of the gene. Improvement of gene transcription efficiency and translation efficiency can be achieved, for example, by altering an expression regulatory sequence. “Expression regulatory sequence” is a general term for sites that affect gene expression. Examples of the expression control sequence include a promoter, Shine-Dalgarno (SD) sequence (also referred to as ribosome binding site (RBS)), and a spacer region between RBS and the start codon. The expression regulatory sequence can be determined using a promoter search vector or gene analysis software such as GENETYX. These expression regulatory sequences can be modified, for example, by a method using a temperature sensitive vector or a Red driven integration method (WO2005 / 010175).

Improvement of gene transcription efficiency can be achieved, for example, by replacing a promoter of a gene on a chromosome with a stronger promoter. By “stronger promoter” is meant a promoter that improves transcription of the gene over the native wild-type promoter. Examples of stronger promoters include the known high expression promoters T7 promoter, trp promoter, lac promoter, thr promoter, thr promoter, tac promoter, trc promoter, tet promoter, araBAD promoter, rpoH promoter, PR promoter, and PL promoter. Can be mentioned. As a more powerful promoter, a highly active promoter of a conventional promoter may be obtained by using various reporter genes. For example, the activity of the promoter can be increased by bringing the -35 and -10 regions in the promoter region closer to the consensus sequence (WO 00/18935). Examples of the highly active promoter include various tac-like promoters (Katashkina JI et al. Russian Patent application 2006134574) and pnlp8 promoter (WO2010 / 027045). Methods for evaluating promoter strength and examples of strong promoters are described in Goldstein et al. (Prokaryotickpromoters in biotechnology. Biotechnol. Annu. Rev.,. 1, 105-128 (1995)).

Improvement of gene translation efficiency can be achieved, for example, by replacing the Shine-Dalgarno (SD) sequence (also referred to as ribosome binding site (RBS)) of the gene on the chromosome with a stronger SD sequence. By “a stronger SD sequence” is meant an SD sequence in which the translation of mRNA is improved over the originally existing wild-type SD sequence. As a stronger SD sequence, for example, RBS of gene 10 derived from phage T7 can be mentioned (Olins P. O. et al, Gene, 1988, 73, 227-235). Furthermore, substitution of several nucleotides in the spacer region between the RBS and the start codon, particularly the sequence immediately upstream of the start codon (5'-UTR), or insertion or deletion, contributes to mRNA stability and translation efficiency. It is known to have a great influence, and the translation efficiency of a gene can be improved by modifying them.

Improvement of gene translation efficiency can also be achieved, for example, by codon modification. In Escherichia coli, etc., there is a clear codon bias among the 61 amino acid codons found in the population of mRNA molecules, and the abundance of a tRNA seems to be directly proportional to the frequency of use of the corresponding codon. (Kane, JF, Curr. Opin. Biotechnol., 6 (5), 494-500 (1995)). That is, if a large amount of mRNA containing an excessive rare codon is present, translation problems may occur. Recent studies suggest that, inter alia, clusters of AGG / AGA, CUA, AUA, CGA, or CCC codons can reduce both the amount and quality of the synthesized protein. Such a problem can occur particularly during the expression of heterologous genes. Therefore, when performing heterologous expression of a gene, the translation efficiency of the gene can be improved by replacing rare codons present in the gene with synonymous codons that are used more frequently. That is, the introduced gene may be modified to have an optimal codon according to, for example, the codon usage frequency of the host to be used. Codon substitution can be performed, for example, by a site-specific mutagenesis method in which a target mutation is introduced into a target site of DNA. As site-directed mutagenesis, a method using PCR (Higuchi, R., 61, in PCR technology, rlErlich, H. A. Eds., Stockton press (1989); Carter, P., ethMeth. In Enzymol., 154, 382 (1987)) and methods using phage (Kramer, W. and Frits, H. J., Meth. In Enzymol., 154, 350 (1987); Kunkel, T. A. et al., Meth In Enzymol., 154, 367 (1987)). Alternatively, gene fragments in which codons have been replaced may be fully synthesized. The frequency of codon usage in various organisms can be found in the “Codon Usage Database” (http://www.kazusa.or.jp/codon; Nakamura, Y. et al, Nucl. Acids Res., 28, 292 (2000)) Is disclosed.

Also, the increase in gene expression can be achieved by amplifying a regulator that increases gene expression or by deleting or weakening a regulator that decreases gene expression.

The techniques for increasing gene expression as described above may be used alone or in any combination.

Further, the modification that increases the activity of the protein can be achieved, for example, by enhancing the specific activity of the protein. Specific activity enhancement also includes the reduction and elimination of feedback inhibition. Proteins with enhanced specific activity can be obtained by searching for various organisms, for example. Alternatively, a highly active protein may be obtained by introducing a mutation into a conventional protein. The introduced mutation may be, for example, a substitution, deletion, insertion or addition of one or several amino acids at one or several positions of the protein. Mutation can be introduced by, for example, the site-specific mutation method as described above. Moreover, you may introduce | transduce a variation | mutation by a mutation process, for example. Mutation treatments include X-ray irradiation, UV irradiation, and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), ethylmethanesulfonate (EMS), and methylmethanesulfonate (MMS). ) And the like. Alternatively, DNA may be directly treated with hydroxylamine in vitro to induce random mutations. The enhancement of specific activity may be used alone or in any combination with the above-described method for enhancing gene expression.

The method of transformation is not particularly limited, and a conventionally known method can be used. For example, as reported for Escherichia coli K-12, recipient cells are treated with calcium chloride to increase DNA permeability (Mandel, M. and Higa, A., J. Mol. Biol. 1970, 53, 159-162) and methods for introducing competent cells from proliferating cells and introducing DNA as reported for Bacillus subtilis (Duncan, C. H., Wilson, G. A. and Young, F. E .., 1997. Gene 1: 153-167) can be used. Alternatively, DNA-receptive cells, such as those known for Bacillus subtilis, actinomycetes, and yeast, can be made into protoplasts or spheroplasts that readily incorporate recombinant DNA into recombinant DNA. Introduction method (Chang, S. and Choen, SN, 1979. Mol. Gen. Genet. 168: 111-115; Bibb, M. J., Ward, J. M. and Hopwood, O. A. 1978. Nature 274: 398-400; Hinnen, A., Hicks, J. B. and Fink, G. R. 1978. Proc. Natl.Acad. Sci. USA 75: 1929-1933) can also be applied. Alternatively, an electric pulse method (Japanese Patent Laid-Open No. 2-207791) as reported for coryneform bacteria can also be used.

The increase in protein activity can be confirmed by measuring the activity of the protein.

The increase in protein activity can also be confirmed by confirming that the expression of the gene encoding the protein has increased. An increase in gene expression can be confirmed by confirming that the transcription amount of the gene has increased, or by confirming that the amount of protein expressed from the gene has increased.

It can be confirmed that the transcription amount of the gene has increased by comparing the amount of mRNA transcribed from the gene with an unmodified strain such as a wild strain or a parent strain. Methods for assessing the amount of mRNA include Northern hybridization, RT-PCR, etc. (Sambrook, J., et al., Molecular Cloning: A Laboratory Manual / Third Edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor ( USA), 2001). The amount of mRNA may be increased by, for example, 1.5 times or more, 2 times or more, or 3 times or more, compared to the unmodified strain.

Confirmation that the amount of protein has increased can be performed by Western blotting using an antibody (Molecular Cloning (Cold Spring Harbor Laboratory Press, Cold Spring Harbor (USA), 2001)). The amount of protein may be increased by, for example, 1.5 times or more, 2 times or more, or 3 times or more, compared to the unmodified strain.

In addition to enhancing the activity of aconitase and acetaldehyde dehydrogenase, the above-described method for increasing the activity of a protein can enhance the activity of any protein, such as an L-amino acid biosynthetic enzyme, or can activate any gene, for example, any of these proteins. It can be used to enhance the expression of the encoding gene.

<1-6> Technique for reducing protein activity A technique for reducing protein activity is described below.

“Protein activity decreases” means that the activity per cell of the protein is decreased compared to wild-type strains and parental unmodified strains, and the activity is completely lost. including. Specifically, “the activity of the protein is decreased” means that the number of molecules per cell of the protein is decreased and / or the function per molecule of the protein compared to the unmodified strain. Means that it is decreasing. In other words, “activity” in the case of “decrease in protein activity” means not only the catalytic activity of the protein but also the transcription amount (mRNA amount) or translation amount (protein amount) of the gene encoding the protein. May be. Note that “the number of molecules per cell of the protein is decreased” includes a case where the protein does not exist at all. Moreover, “the function per molecule of the protein is reduced” includes the case where the function per molecule of the protein is completely lost. The activity of the protein is not particularly limited as long as it is lower than that of the non-modified strain. For example, it is 50% or less, 20% or less, 10% or less, 5% or less, or 0, compared to the non-modified strain. %.

The modification that reduces the activity of the protein is achieved, for example, by reducing the expression of a gene encoding the protein. “Gene expression decreases” means that the expression level of the gene per cell decreases as compared to an unmodified strain such as a wild strain or a parent strain. “Gene expression decreases” specifically means that the amount of gene transcription (mRNA amount) decreases and / or the amount of gene translation (protein amount) decreases. Good. “Gene expression decreases” includes the case where the gene is not expressed at all. In addition, “the expression of the gene is reduced” is also referred to as “the expression of the gene is weakened”. Gene expression may be reduced to, for example, 50% or less, 20% or less, 10% or less, 5% or less, or 0% compared to an unmodified strain.

The decrease in gene expression may be due to, for example, a decrease in transcription efficiency, a decrease in translation efficiency, or a combination thereof. For example, gene expression can be reduced by altering expression regulatory sequences such as the promoter of the gene, Shine-Dalgarno (SD) sequence (also called ribosome binding site (RBS)), spacer region between RBS and start codon. Can be achieved. In the case of modifying the expression control sequence, the expression control sequence is preferably modified by 1 base or more, more preferably 2 bases or more, particularly preferably 3 bases or more. Further, part or all of the expression regulatory sequence may be deleted. In addition, reduction of gene expression can be achieved, for example, by manipulating factors involved in expression control. Factors involved in expression control include small molecules (such as inducers and inhibitors) involved in transcription and translation control, proteins (such as transcription factors), nucleic acids (such as siRNA), and the like. In addition, reduction of gene expression can be achieved, for example, by introducing a mutation that reduces gene expression into the coding region of the gene. For example, gene expression can be reduced by replacing codons in the coding region of the gene with synonymous codons that are used less frequently in the host. In addition, for example, gene expression itself may be reduced by gene disruption as described below.

Further, the modification that decreases the activity of the protein can be achieved, for example, by destroying a gene encoding the protein. “Gene is disrupted” means that the gene is modified so that it does not produce a normally functioning protein. “Does not produce a protein that functions normally” includes the case where no protein is produced from the same gene, or the case where a protein whose function (activity or property) per molecule is reduced or lost is produced from the same gene. It is.

Gene disruption can be achieved, for example, by deleting part or all of the coding region of the gene on the chromosome. Furthermore, the entire gene including the sequences before and after the gene on the chromosome may be deleted. The region to be deleted may be any region such as an N-terminal region, an internal region, or a C-terminal region as long as a decrease in protein activity can be achieved. Usually, the longer region to be deleted can surely inactivate the gene. Moreover, it is preferable that the reading frames of the sequences before and after the region to be deleted do not match.

In addition, gene disruption is, for example, introducing an amino acid substitution (missense mutation) into a coding region of a gene on a chromosome, introducing a stop codon (nonsense mutation), or adding or deleting 1 to 2 bases. It can also be achieved by introducing a frameshift mutation (Journal of Biological Chemistry 272: 8611-8617 (1997), Proceedings of the National Academy of Sciences, USA 95 5511-5515 (1998), Journal of Biological Chemistry 26 116, 20833-20839 (1991)).

Also, gene disruption can be achieved, for example, by inserting another sequence into the coding region of the gene on the chromosome. The insertion site may be any region of the gene, but the longer the inserted sequence, the more reliably the gene can be inactivated. Moreover, it is preferable that the reading frames of the sequences before and after the insertion site do not match. The other sequence is not particularly limited as long as it reduces or eliminates the activity of the encoded protein, and examples thereof include marker genes such as antibiotic resistance genes and genes useful for the production of target substances.

To modify a gene on a chromosome as described above, a deletion type gene modified so as not to produce a normally functioning protein is prepared, and a host is transformed with a recombinant DNA containing the deletion type gene. This can be achieved by causing homologous recombination between the deletion type gene and the wild type gene on the chromosome to replace the wild type gene on the chromosome with the deletion type gene. At this time, the recombinant DNA can be easily manipulated by including a marker gene in accordance with a trait such as auxotrophy of the host. Deletion-type genes include genes with deletion of all or part of the gene, genes with missense mutations, genes with transposon and marker genes inserted, genes with nonsense mutations, and frameshift mutations. Gene. Even if the protein encoded by the deletion-type gene is produced, it has a three-dimensional structure different from that of the wild-type protein, and its function is reduced or lost. Gene disruption by gene replacement using such homologous recombination has already been established, and a method called “Red-driven integration” (Datsenko, K. A, and Wanner, B. L. Proc .Natl. Acad. Sci. U S A. 97: 6640-6645 (2000)), Red-driven integration method and λ phage-derived excision system (Cho, E. H., Gumport, R. I., Gardner, J F. J. Bacteriol. 184: 5200-5203 (2002)), a method using linear DNA such as a method (see WO2005 / 010175), a method using a plasmid containing a temperature-sensitive replication origin, There are a method using a plasmid capable of conjugation transfer and a method using a suicide vector which does not have an origin of replication and functions in a host (US Pat. No. 6,303,383, Japanese Patent Laid-Open No. 05-007491).

Further, the modification that reduces the activity of the protein may be performed by, for example, a mutation treatment. Mutation treatments include X-ray irradiation, UV irradiation, and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), ethylmethanesulfonate (EMS), and methylmethanesulfonate (MMS). ) And the like.

When the protein functions as a complex composed of a plurality of subunits, all of the plurality of subunits may be modified or only a part may be modified as long as the activity of the protein decreases as a result. . That is, for example, all of a plurality of genes encoding these subunits may be destroyed, or only a part of them may be destroyed. In addition, when a plurality of isozymes are present in a protein, as long as the activity of the protein is reduced as a result, all the activities of the plurality of isozymes may be reduced, or only a part of the activities may be reduced. That is, for example, all of a plurality of genes encoding these isozymes may be destroyed, or only a part of them may be destroyed.

The decrease in the activity of the protein can be confirmed by measuring the activity of the protein.

The decrease in protein activity can also be confirmed by confirming that the expression of the gene encoding the protein has decreased. The decrease in gene expression can be confirmed by confirming that the transcription amount of the gene has decreased, or confirming that the amount of protein expressed from the gene has decreased.

It can be confirmed that the amount of transcription of the gene has been reduced by comparing the amount of mRNA transcribed from the same gene with that of the unmodified strain. Examples of methods for evaluating the amount of mRNA include Northern hybridization, RT-PCR and the like (Molecular Cloning (Cold Spring Laboratory Press, Cold Spring Harbor (USA), 2001)). The amount of mRNA may be reduced to, for example, 50% or less, 20% or less, 10% or less, 5% or less, or 0% compared to the unmodified strain.

Confirmation that the amount of protein has decreased can be performed by Western blotting using an antibody (Molecular Cloning (Cold Spring Harbor Laboratory Press, Cold Spring Harbor (USA), 2001)). The amount of protein may be reduced to, for example, 50% or less, 20% or less, 10% or less, 5% or less, or 0% compared to the unmodified strain.

It can be confirmed that the gene has been destroyed by determining part or all of the nucleotide sequence, restriction enzyme map, full length, etc. of the gene according to the means used for the destruction.

The above-described method for reducing the activity of a protein involves reducing the activity of any protein, for example, an enzyme that catalyzes a reaction that branches from the biosynthetic pathway of the target L-amino acid to produce a compound other than the target L-amino acid. , And can be used to reduce the expression of any gene, for example, a gene encoding any of these proteins.

<2> Method for Producing L-Amino Acid of the Present Invention The method of the present invention comprises culturing the bacterium of the present invention in a medium containing ethanol and producing and accumulating L-amino acid in the medium or in the microbial cells. And a method for producing an L-amino acid, which comprises collecting the L-amino acid from the medium or cells. In the present invention, one L-amino acid may be produced, or two or more L-amino acids may be produced.

The medium to be used is not particularly limited as long as it contains ethanol and the bacteria of the present invention can grow and L-amino acids are produced. As the medium, for example, a normal medium used for culturing microorganisms such as bacteria can be used. The medium may contain, in addition to ethanol, a component selected from a carbon source, a nitrogen source, a phosphate source, a sulfur source, and other various organic components and inorganic components as necessary. The type and concentration of the medium component may be appropriately set according to various conditions such as the type of bacteria used and the type of L-amino acid to be produced.

In the method of the present invention, ethanol may or may not be used as the sole carbon source. That is, in the method of the present invention, other carbon sources may be used in combination with ethanol. Other carbon sources are not particularly limited as long as they can be assimilated by the bacterium of the present invention to produce L-amino acids. As other carbon sources, specifically, sugars such as glucose, fructose, sucrose, lactose, galactose, arabinose, waste molasses, starch hydrolyzate, biomass hydrolyzate, acetic acid, fumaric acid, citric acid, Examples thereof include organic acids such as succinic acid and malic acid, alcohols such as glycerol and crude glycerol, and fatty acids. When other carbon sources are used, the ratio of ethanol in the total carbon source is, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, preferably 30% by weight or more, more preferably 50% by weight. It may be above. As another carbon source, one type of carbon source may be used, or two or more types of carbon sources may be used in combination.

The concentration of the carbon source in the medium is not particularly limited as long as the bacterium of the present invention can grow and L-amino acid is produced. The concentration of the carbon source in the medium is preferably as high as possible as long as the production of L-amino acid is not inhibited. The initial concentration of the carbon source in the medium may be, for example, usually 1 to 30% (w / v), preferably 3 to 10% (w / v). Moreover, you may add a carbon source additionally according to consumption of the carbon source accompanying progress of fermentation.

Specific examples of the nitrogen source include ammonium salts such as ammonium sulfate, ammonium chloride, and ammonium phosphate, organic nitrogen sources such as peptone, yeast extract, meat extract, and soybean protein degradation product, ammonia, and urea. Ammonia gas or ammonia water used for pH adjustment may be used as a nitrogen source. As the nitrogen source, one kind of nitrogen source may be used, or two or more kinds of nitrogen sources may be used in combination.

Specific examples of the phosphoric acid source include phosphates such as potassium dihydrogen phosphate and dipotassium hydrogen phosphate, and phosphate polymers such as pyrophosphoric acid. As the phosphoric acid source, one type of phosphoric acid source may be used, or two or more types of phosphoric acid sources may be used in combination.

Specific examples of the sulfur source include inorganic sulfur compounds such as sulfate, thiosulfate, and sulfite, and sulfur-containing amino acids such as cysteine, cystine, and glutathione. As the sulfur source, one kind of sulfur source may be used, or two or more kinds of sulfur sources may be used in combination.

Other various organic and inorganic components include, for example, inorganic salts such as sodium chloride and potassium chloride; trace metals such as iron, manganese, magnesium and calcium; vitamin B1, vitamin B2, vitamin B6 and nicotine Examples include vitamins such as acid, nicotinamide, and vitamin B12; amino acids; nucleic acids; and organic components such as peptone, casamino acid, yeast extract, and soybean protein degradation products containing these. As other various organic components and inorganic components, one component may be used, or two or more components may be used in combination.

Moreover, when using an auxotrophic mutant strain that requires an amino acid or the like for growth, it is preferable to supplement nutrients required for the medium. For example, L-lysine producing bacteria often have an enhanced L-lysine biosynthetic pathway and weakened L-lysine resolution. Therefore, when culturing such L-lysine-producing bacteria, for example, one or more amino acids selected from L-threonine, L-homoserine, L-isoleucine, and L-methionine are supplemented to the medium. Is preferred.

Culture conditions are not particularly limited as long as the bacterium of the present invention can grow and L-amino acids are produced. The culture can be performed, for example, under normal conditions used for culture of bacteria such as Escherichia coli. The culture conditions may be appropriately set according to various conditions such as the type of bacteria used and the type of L-amino acid to be produced.

Cultivation can be performed using a liquid medium. When culturing, the culture medium of the bacterium of the present invention cultured in a solid medium such as an agar medium may be directly inoculated into a liquid medium, or the bacterium of the present invention seeded in a liquid medium is used as a liquid for main culture. The medium may be inoculated. That is, the culture may be performed separately for seed culture and main culture. In that case, the culture conditions of the seed culture and the main culture may or may not be the same. The amount of the bacterium of the present invention contained in the medium at the start of culture is not particularly limited. For example, a seed culture solution having an OD660 of 4 to 8 may be added at 0.1 to 30% by mass, preferably 1 to 10% by mass with respect to the medium for main culture at the start of culture.

Culture can be performed by batch culture, fed-batch culture, continuous culture, or a combination thereof. The culture medium at the start of the culture is also referred to as “initial culture medium”. A medium supplied to a culture system (fermentor) in fed-batch culture or continuous culture is also referred to as “fed-batch medium”. In addition, supplying a feeding medium to a culture system in fed-batch culture or continuous culture is also referred to as “fed-batch”. In addition, when culture | cultivation is performed by dividing into seed culture and main culture, for example, both seed culture and main culture may be performed by batch culture. Further, for example, seed culture may be performed by batch culture, and main culture may be performed by fed-batch culture or continuous culture.

In the present invention, each medium component may be contained in the initial medium, the fed-batch medium, or both. The type of component contained in the initial culture medium may or may not be the same as the type of component contained in the fed-batch medium. Moreover, the density | concentration of each component contained in a starting culture medium may be the same as the density | concentration of each component contained in a feeding culture medium, and may not be so. Moreover, you may use the 2 or more types of feeding culture medium from which the kind and / or density | concentration of a component to contain differ. For example, when multiple feedings are performed intermittently, the types and / or concentrations of the components contained in each feeding medium may or may not be the same.

The ethanol concentration in the medium is not particularly limited as long as the bacterium of the present invention can use ethanol as a carbon source. For example, ethanol may be contained in the medium at a concentration of 10 w / v% or less, preferably 5 w / v% or less, more preferably 2 w / v% or less. Further, ethanol may be contained in the medium at a concentration of, for example, 0.2 w / v% or more, preferably 0.5 w / v% or more, more preferably 1.0 w / v% or more. Ethanol may be contained in the starting medium, fed-batch medium, or both in the concentration ranges exemplified above.

When ethanol is contained in the fed-batch medium, for example, the ethanol concentration in the medium after fed-batch is 5 w / v% or less, preferably 2 w / v% or less, more preferably 1 w / v%. It may be contained in a fed-batch medium so that In the case where ethanol is contained in the fed-batch medium, for example, the ethanol concentration in the medium after fed is 0.01 w / v% or more, preferably 0.02 w / v% or more, more preferably You may contain in a feeding medium so that it may become 0.05 w / v% or more.

Ethanol may be contained in the concentration range exemplified above when it is used only as a carbon source. Moreover, ethanol may be contained in the concentration range exemplified above when another carbon source is used in combination. In addition, when other carbon sources are used in combination, ethanol may be contained in a concentration range that is appropriately modified from the above-described concentration range, for example, depending on the ratio of ethanol in the total carbon source.

Ethanol may or may not be contained in the medium in a certain concentration range during the entire culture period. For example, ethanol may be insufficient for some period. “Insufficient” means that the required amount is not satisfied. For example, the concentration in the medium may be zero. “Partial period” refers to, for example, a period of 1% or less, a period of 5% or less, a period of 10% or less, a period of 20% or less, a period of 30% or less, or a period of the whole culture period, or It may be a period of 50% or less. In addition, "the whole period of culture | cultivation" may mean the whole period of main culture, when culture | cultivation is performed by dividing into seed culture and main culture. It is preferred that other carbon sources be satisfied during the period of ethanol shortage. Thus, even if ethanol is insufficient for a part of the period, it is included in “culturing bacteria in a medium containing ethanol” as long as there is a culture period in a medium containing ethanol.

The concentration of various components such as ethanol is determined by gas chromatography (Hashimoto, K. et al. 1996. Biosci. Biotechnol. Biochem. 70: 22-30) or HPLC (Lin, J. T. et al. 1998. J. Chromatogr. A. 808: 43-49).

The culture can be performed aerobically, for example. For example, the culture can be performed by aeration culture or shaking culture. The oxygen concentration may be controlled to, for example, 5 to 50%, preferably about 10% of the saturated oxygen concentration. The pH of the medium may be, for example, pH 3 to 10, preferably pH 4.0 to 9.5. During the culture, the pH of the medium can be adjusted as necessary. The pH of the medium is adjusted using various alkaline or acidic substances such as ammonia gas, ammonia water, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, magnesium carbonate, sodium hydroxide, calcium hydroxide, magnesium hydroxide, etc. can do. The culture temperature may be, for example, 20 to 45 ° C, preferably 25 ° C to 37 ° C. The culture period may be, for example, 10 hours to 120 hours. The culture may be continued, for example, until the carbon source in the medium is consumed or until the activity of the bacterium of the present invention is lost. By culturing the bacterium of the present invention under such conditions, L-amino acids accumulate in the cells and / or in the medium.

In fed-batch culture or continuous culture, fed-batch may be continued throughout the entire culture period or only during a part of the culture period. In addition, in fed-batch culture or continuous culture, multiple feedings may be performed intermittently.

When a plurality of feedings are intermittently performed, the duration of one feeding is, for example, 30% or less, preferably 20% or less, more preferably 10% of the total time of the plurality of feedings. The start and stop of fed batch may be repeated so that:

In addition, when multiple feedings are performed intermittently, the second and subsequent feedings are controlled so that they are started when the carbon source in the fermentation medium is depleted in the immediately preceding feeding stop phase. Can automatically maintain the carbon source concentration in the fermentation medium at a low level (US Pat. No. 5,912,113). Carbon source depletion can be detected, for example, by increasing pH or increasing dissolved oxygen concentration.

In continuous culture, extraction of the culture solution may be continued throughout the entire culture period, or may be continued only during a part of the culture period. Further, in continuous culture, a plurality of culture solutions may be extracted intermittently. Extraction and feeding of the culture solution may or may not be performed simultaneously. For example, the feeding may be performed after the culture solution is extracted, or the culture solution may be extracted after the feeding. The amount of the culture solution to be withdrawn is preferably the same as the amount of the medium to be fed. Here, the “same amount” may be, for example, an amount of 93 to 107% with respect to the amount of medium to be fed.

When the culture solution is continuously extracted, it is preferable to start the extraction simultaneously with the feeding or after the start of the feeding. For example, the withdrawal may be started within 5 hours, preferably within 3 hours, more preferably within 1 hour after the start of fed-batch.

When the culture solution is withdrawn intermittently, when the planned L-amino acid concentration is reached, a part of the culture solution is withdrawn to recover the L-amino acid, and the culture is continued by feeding a new medium. Is preferred.

In addition, the bacterial cells can be reused by recovering L-amino acid from the extracted culture medium and recirculating the filtration residue containing the bacterial cells in the fermenter (French Patent No. 2669935). ).

In addition, when producing L-glutamic acid, it is also possible to carry out the culture while precipitating L-glutamic acid in the medium using a liquid medium adjusted to conditions under which L-glutamic acid is precipitated. The conditions under which L-glutamic acid precipitates are, for example, pH 5.0 to 3.0, preferably pH 4.9 to 3.5, more preferably pH 4.9 to 4.0, and particularly preferably around pH 4.7. (European Patent Application Publication No. 1078989). In addition, culture | cultivation may be performed at the said pH in the whole period, and may be performed at the said pH only for a part of period. The “partial period” may be, for example, a period of 50% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 99% or more of the entire culture period.

Further, when a basic amino acid such as L-lysine is produced, a method of fermenting basic amino acid using bicarbonate ion and / or carbonate ion as a main counter ion of basic amino acid may be used. (Unexamined-Japanese-Patent No. 2002-65287, US2002-0025564A, EP1813677A). According to these methods, basic amino acids can be produced while reducing the amount of sulfate ions and / or chloride ions that have been conventionally used as counter ions for basic amino acids.

In this method, the pH of the medium during the culture is controlled to 6.5 to 9.0, preferably 6.5 to 8.0, and the pH of the medium at the end of the culture is controlled to 7.2 to 9.0. In addition, there is a culture period in which bicarbonate ions and / or carbonate ions are present in the medium at 20 mM or more, preferably 30 mM or more, more preferably 40 mM or more. In order to make the necessary amount of bicarbonate ions and / or carbonate ions as counter ions of basic amino acids exist in the medium, the pressure in the fermenter during the fermentation is controlled to be positive, and the carbon dioxide gas is cultured. It is preferred to feed the liquid or both.

In order to control the pressure in the fermenter during fermentation to be positive, for example, the supply air pressure may be set higher than the exhaust pressure. By making the pressure in the fermenter positive, the carbon dioxide gas generated by fermentation dissolves in the culture solution to produce bicarbonate ions and / or carbonate ions, and the bicarbonate ions and / or carbonate ions are counter ions of basic amino acids. Can be. Specifically, the fermenter pressure is 0.03 to 0.2 MPa, preferably 0.05 to 0.15 MPa, more preferably 0.1 to 0.3 MPa in terms of gauge pressure (differential pressure relative to atmospheric pressure). Is mentioned. When carbon dioxide is supplied to the culture solution, for example, pure carbon dioxide or a mixed gas containing 5% by volume or more of carbon dioxide may be blown into the culture solution. Fermenter pressure, carbon dioxide supply, and limited air supply can be determined, for example, by measuring the pH of the medium, the concentration of bicarbonate and / or carbonate ions in the medium, or the concentration of ammonia in the medium. Can be determined.

In conventional methods for producing basic amino acids, sulfate ions and / or chloride ions are used as counter ions for basic amino acids, so a sufficient amount of ammonium sulfate and / or ammonium chloride, or sulfate such as protein as a nutrient component Degradation products and / or hydrochloric acid degradation products were added to the medium. Therefore, a large amount of sulfate ion and / or chloride ion was present in the medium, and the weakly acidic carbonate ion concentration was extremely low, on the order of ppm.

On the other hand, the above method (Japanese Patent Application Laid-Open No. 2002-65287, US2002-0025564A, EP1813677A) reduces the use amount of these sulfate ions and chloride ions, dissolves carbon dioxide released by microorganisms during fermentation in the medium, It is characterized by use.

That is, in the same method, one of the purposes is to reduce the amount of sulfate ions and / or chloride ions used, so the total molar concentration of sulfate ions and chloride ions contained in the medium is usually 700 mM or less, preferably 500 mM or less, more preferably 300 mM or less, further preferably 200 mM or less, particularly preferably 100 mM or less. By reducing the concentration of sulfate ions and / or chloride ions, bicarbonate ions and / or carbonate ions can be more easily present in the medium. That is, in this method, compared to the conventional method, it is possible to keep the pH of the medium for making the amount of bicarbonate ions and / or carbonate ions necessary for counter ions of basic amino acids present in the medium low. Become.

In this method, the concentration of bicarbonate ions and / or anions other than carbonate ions (also referred to as other anions) in the medium only needs to include an amount necessary for the growth of basic amino acid-producing bacteria. Preferably, it is low. Examples of other anions include chloride ions, sulfate ions, phosphate ions, ionized organic acids, and hydroxide ions. The total molar concentration of other anions contained in the medium is usually 900 mM or less, preferably 700 mM or less, more preferably 500 mM or less, still more preferably 300 mM or less, and particularly preferably 200 mM or less.

In this method, it is not necessary to add sulfate ions or chloride ions to the medium beyond the amount necessary for growth of basic amino acid-producing bacteria. Preferably, an appropriate amount of ammonium sulfate or the like is fed to the medium at the beginning of the culture, and the feed is stopped during the culture. Or you may feed ammonium sulfate etc., maintaining the balance with the dissolved amount of the carbonate ion and / or bicarbonate ion in a culture medium. Alternatively, ammonia may be fed to the medium as a nitrogen source for basic amino acids. For example, when pH is controlled with ammonia, ammonia supplied to increase the pH can be used as a nitrogen source for basic amino acids. Ammonia can be supplied to the medium alone or with other gases.

In this method, the total ammonia concentration in the medium is preferably controlled to a concentration that does not inhibit the production of basic amino acids. The total ammonia concentration that “does not inhibit the production of basic amino acids” is, for example, preferably 50% or more, more preferably compared to the yield and / or productivity in the case of producing basic amino acids under optimum conditions. Examples include a total ammonia concentration that provides a yield and / or productivity of 70% or more, particularly preferably 90% or more. Specifically, the total ammonia concentration in the medium is preferably a concentration of 300 mM or less, more preferably 250 mM, particularly preferably 200 mM or less. The degree of ammonia dissociation decreases with increasing pH. Undissociated ammonia is more toxic to bacteria than ammonium ions. Therefore, the upper limit of the total ammonia concentration also depends on the pH of the culture solution. That is, the higher the pH of the culture solution, the lower the allowable total ammonia concentration. Therefore, the total ammonia concentration that does not inhibit the production of basic amino acids is preferably set for each pH. However, the total ammonia concentration range allowed at the highest pH during the culture may be used as the total ammonia concentration range throughout the culture period.

On the other hand, the total ammonia concentration as a nitrogen source necessary for the growth of basic amino acid-producing bacteria and the production of basic amino acids does not continue to be a state where ammonia is depleted during the culture, and the microorganism is due to a shortage of nitrogen source. As long as the productivity of the target substance is not reduced by the above, it is not particularly limited and can be set as appropriate. For example, the ammonia concentration may be measured over time during the culture, and a small amount of ammonia may be added to the medium when the ammonia in the medium is depleted. The ammonia concentration when ammonia is added is not particularly limited. For example, the total ammonia concentration is preferably 1 mM or more, more preferably 10 mM or more, and particularly preferably 20 mM or more.

In the same method, the medium may contain cations other than basic amino acids. Examples of cations other than basic amino acids include K, Na, Mg, and Ca derived from medium components. The total molar concentration of cations other than basic amino acids is preferably 50% or less of the molar concentration of total cations.

The formation of L-amino acid can be confirmed by a known method used for detection or identification of a compound. Examples of such a method include HPLC, LC / MS, GC / MS, and NMR. These methods can be used in appropriate combination.

The produced L-amino acid can be recovered by a known method used for separation and purification of compounds. Examples of such a method include an ion exchange resin method, a membrane treatment method, a precipitation method, and a crystallization method. These methods can be used in appropriate combination. In the case where L-amino acid accumulates in the microbial cells, for example, the microbial cells are crushed with ultrasonic waves, and the microbial cells are removed by centrifugation from the supernatant obtained by ion exchange resin method or the like. Amino acids can be recovered. The recovered L-amino acid may be a free form, a salt thereof, or a mixture thereof. Examples of the salt include sulfate, hydrochloride, carbonate, ammonium salt, sodium salt, and potassium salt. For example, L-lysine may be free L-lysine, L-lysine sulfate, L-lysine hydrochloride, L-lysine carbonate, or a mixture thereof. Further, for example, L-glutamic acid may be free L-glutamic acid, sodium L-glutamate (MSG), ammonium L-glutamate (monoammonium L-glutamate), or a mixture thereof. . For example, in the case of L-glutamic acid, ammonium L-glutamate in the fermentation broth is crystallized by adding an acid, and equimolar sodium hydroxide is added to the crystals to obtain sodium L-glutamate (MSG). In addition, you may decolorize by adding activated carbon before and after the crystallization (see Industrial crystallization of sodium glutamate, Journal of the Seawater Society of Japan, Vol. 56, No. 5, Tetsuya Kawakita).

If L-amino acid is precipitated in the medium, it can be recovered by centrifugation or filtration. The L-amino acid precipitated in the medium may be isolated together after crystallization of the L-amino acid dissolved in the medium.

The recovered L-amino acid may contain components other than the L-amino acid, such as bacterial cells, medium components, water, and bacterial metabolic byproducts. The purity of the recovered L-amino acid is, for example, 30% (w / w) or higher, 50% (w / w) or higher, 70% (w / w) or higher, 80% (w / w) or higher, 90% (W / w) or more, or 95% (w / w) or more.

Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1] Giving ethanol-assimilating ability to L-lysine-producing bacterium AJIK01 strain (NITE BP-01520) With L-lysine-producing bacterium Escherichia coli AJIK01 strain (NITE BP-01520) as a parent strain, An L-lysine-producing bacterium AJIK01m2 strain to which ethanol assimilation was imparted was constructed.

First, P1 lysate was obtained from Escherichia coli MG1655-att-tet-P _L-tac adhE ^* strain (WO2011 / 096554) according to a conventional method, and P1 transduction was performed using AJIK01 strain (NITE BP-01520) as a host. ^* AJIK01 att-tet-PL _-tac adhE ^* strain into which a cassette containing the gene was introduced was obtained. The adhE ^* gene is a mutant type adhE encoding a mutant AdhE protein in which six mutations of Glu568Lys, Glu22Gly, Met236Val, Tyr461Cys, Ile554Ser, and Ala786Val are introduced into the wild type AdhE protein of the Escherichia coli K12 MG1655 strain shown in SEQ ID NO: 46. It is a gene (WO2008 / 010565).

Next, a helper plasmid pMW-intxis-ts (see US Patent Application Publication No. 20060141586) was used to remove the att-tet sequence introduced upstream of the P _L-tac promoter. pMW-intxis-ts is a temperature-sensitive replication plasmid carrying a gene encoding λ phage integrase (Int) and a gene encoding excisionase (Xis). Competent cells of the AJIK01 att-tet-PL _-tac adhE ^* strain obtained above were prepared according to a conventional method, transformed with the helper plasmid pMW-intxis-ts, and 100 mg / L ampicillin at 30 ° C. Was plated on an LB agar medium containing, and an ampicillin resistant strain was selected. In order to remove the pMW-intxis-ts plasmid, the transformant was cultured on LB agar medium at 42 ° C. The resulting colonies were tested for ampicillin resistance and tetracycline resistance, and strains sensitive to ampicillin and tetracycline were obtained. The obtained strain is a P _L-tac adhE ^* introduced strain in which the att-tet sequence has been removed from the chromosome genome and pMW-intxis-ts has been removed. This strain was named AJIK01m2.

In Example 2 Construction of L- lysine-producing bacterium with enhanced expression of acnB gene (1) Construction SEQ ID NO: 2 and SEQ ID NO: 3 in the expression with the promoter P ₁₄ plasmid pMW119-attR-cat-attL- P 14 using the indicated synthetic oligonucleotides as primers, PCR was carried out with the chromosomal DNA of Escherichia coli MG1655 strain as a template to amplify the sequence of gdhA gene containing the promoter P ₁₄ shown in SEQ ID NO: 1. The PCR product was purified, treated with Takara BKL Kit (Takara Bio), ligated to pMW219 (Nippon Gene) digested with SmaI and treated with Takara BKL Kit to obtain plasmid pMW219-P ₁₄ -gdhA It was.

Using the synthetic oligonucleotides shown in SEQ ID NO: 4 and SEQ ID NO: 5 as primers, PCR was performed using pMW219-P ₁₄ -gdhA as a template to amplify the promoter P ₁₄ sequence (P ₁₄ sequence).

PCR was performed using the synthetic oligonucleotides shown in SEQ ID NO: 6 and SEQ ID NO: 7 as primers and the plasmid pMW118-attL-Cm-attR (WO2005 / 010175) as a template, and the sequences attR and attL of the attachment sites of λ phage An attR-cat-attL sequence having a chloramphenicol resistance gene cat in between was amplified.

The pMW119 digested with HindIII and SalI (Nippon Gene), and connecting the attR-cat-attL sequence and P ₁₄ sequences using In-Fusion HD Cloning kit (Takara Bio Inc.), with a promoter P ₁₄ the expression plasmid pMW119-attR-cat-attL- P 14 was constructed.

(2) the acnB gene expression enhancing plasmid pMW119-attR-cat-attL- P 14 -acnB construction SEQ ID NO: synthetic oligonucleotides shown in 8 and SEQ ID NO: 9 using as primers, the chromosome of E. coli MG1655 strain PCR was performed using DNA as a template to amplify a sequence containing the acnB gene. Using synthetic oligonucleotides shown in SEQ ID NO: 10 and SEQ ID NO: 11 as primers, plasmid pMW119-attR-cat-attL- P 14 PCR performed as a template, a linear pMW119-attR-cat-attL- P 14 Amplified. In-Fusion HD Cloning kit by connecting an array with linear pMW119-attR-cat-attL- P 14 containing acnB gene (manufactured by Takara Bio Inc.), expressing the acnB gene under the control of a promoter P ₁₄ Plasmid pMW119-attR-cat-attL-P ₁₄ -acnB was constructed.

The constructed plasmid pMW119-attR-cat-attL-P ₁₄ -acnB was introduced into the AJIK01m2 strain according to a conventional method to obtain AJIK01m2 / pMW119-attR-cat-attL-P ₁₄ -acnB strain. After culturing the obtained strain in LB medium containing 100 mg / L ampicillin at 37 ° C. so that the final OD600≈0.6, add the same amount of 40% glycerol solution as the culture solution, and stir, Aliquots were dispensed and stored at -80 ° C. This is called the glycerol stock of the AJIK01m2 / pMW119-attR-cat-attL-P ₁₄ -acnB strain.

Example 3 acnB and construction of L- lysine-producing bacterium with enhanced expression of both genes of aldB (1) aldB gene expression enhancing plasmid for pMW119-attR-cat-attL- P 14 -aldB Construction SEQ ID NO: 12 Using the synthetic oligonucleotide shown in SEQ ID NO: 13 as a primer, PCR was performed using the chromosomal DNA of Escherichia coli MG1655 strain as a template to amplify the sequence containing the aldB gene. Using synthetic oligonucleotides shown in SEQ ID NO: 10 and SEQ ID NO: 11 as primers, plasmid pMW119-attR-cat-attL- P 14 PCR performed as a template, a linear pMW119-attR-cat-attL- P 14 Amplified. In-Fusion HD Cloning kit by connecting an array with linear pMW119-attR-cat-attL- P 14 comprising aldB gene (manufactured by Takara Bio Inc.), expressing the aldB gene under the control of a promoter P ₁₄ The plasmid pMW119-attR-cat-attL-P ₁₄ -aldB was constructed.

(2) the acnB gene and aldB gene expression enhancing plasmid for pMW119-attR-cat-attL- P 14 -acnB-P 14 -aldB construction SEQ ID NO: synthetic oligonucleotides shown in 14 and SEQ ID NO: 15 using as primers Then, PCR was performed using the plasmid pMW119-attR-cat-attL-P ₁₄ -acnB as a template to amplify the sequence containing P ₁₄ -acnB. PCR was performed using plasmid pMW119-attR-cat-attL-P14-aldB as a template using the synthetic oligonucleotides shown in SEQ ID NO: 16 and SEQ ID NO: 17 as primers, and linear pMW119-attR-cat-attL-P14- aldB was amplified. Using In-Fusion HD Cloning kit (manufactured by Takara Bio Inc.), the sequence containing P ₁₄ -acnB and the linear pMW119-attR-cat-attL-P ₁₄ -aldB are ligated and acnB under the control of promoter P ₁₄ to construct plasmid pMW119-attR-cat-attL- P 14 -acnB-P 14 -aldB express the gene and aldB gene.

The constructed plasmid pMW119-attR-cat-attL-P ₁₄ -acnB-P ₁₄ -aldB was introduced into the AJIK01m2 strain in accordance with a conventional method, and AJIK01m2 / pMW119-attR-cat-attL-P ₁₄ -acnB-P ₁₄ -aldB strain Got. After culturing the obtained strain in LB medium containing 100 mg / L ampicillin at 37 ° C. so that the final OD600≈0.6, add the same amount of 40% glycerol solution as the culture solution, and stir, Aliquots were dispensed and stored at -80 ° C. This is referred to as glycerol stock of AJIK01m2 / pMW119-attR-cat- attL-P 14 -acnB-P 14 -aldB stock.

Example 4 acnA and construction of L- lysine-producing bacterium with enhanced expression of both genes of aldB (1) acnA enhanced gene expression plasmid for pMW119-attR-cat-attL- P 14 -acnA construction SEQ ID NO: 18 PCR was carried out using the chromosomal DNA of Escherichia coli MG1655 strain as a template using the synthetic oligonucleotide shown in SEQ ID NO: 19 as a primer, and the sequence containing the acnA gene was amplified. Using synthetic oligonucleotides shown in SEQ ID NO: 10 and SEQ ID NO: 11 as primers, plasmid pMW119-attR-cat-attL- P 14 PCR performed as a template, a linear pMW119-attR-cat-attL- P 14 Amplified. In-Fusion HD Cloning kit by connecting an array with linear pMW119-attR-cat-attL- P 14 containing acnA gene (manufactured by Takara Bio Inc.), expressing the acnA gene under the control of a promoter P ₁₄ The plasmid pMW119-attR-cat-attL-P ₁₄ -acnA was constructed.

(2) The acnA gene and aldB gene expression enhancing plasmid for pMW119-attR-cat-attL- P 14 -acnA-P 14 -aldB construction SEQ ID NO: synthetic oligonucleotides shown in 14 and SEQ ID NO: 20 is used as a primer the plasmid pMW119-attR-cat-attL- P 14 -acnA PCR performed as a template to amplify the sequence containing the P14-acnA. PCR was performed using plasmid pMW119-attR-cat-attL-P ₁₄ -aldB as a template using the synthetic oligonucleotides shown in SEQ ID NO: 16 and SEQ ID NO: 17 as primers, and linear pMW119-attR-cat-attL-P ₁₄ -aldB was amplified. Using In-Fusion HD Cloning kit (Takara Bio), the sequence containing P ₁₄ -acnA and the linear pMW119-attR-cat-attL-P ₁₄ -aldB are ligated and acnA under the control of promoter P ₁₄ to construct plasmid pMW119-attR-cat-attL- P 14 -acnA-P 14 -aldB express the gene and aldB gene.

The constructed plasmid pMW119-attR-cat-attL-P ₁₄ -acnA-P ₁₄ -aldB was introduced into the AJIK01m2 strain in the usual manner, and AJIK01m2 / pMW119-attR-cat-attL-P ₁₄ -acnA-P ₁₄ -aldB strain Got. After culturing the obtained strain in LB medium containing 100 mg / L ampicillin at 37 ° C. so that the final OD600≈0.6, add the same amount of 40% glycerol solution as the culture solution, and stir, Aliquots were dispensed and stored at -80 ° C. This is referred to as glycerol stock of AJIK01m2 / pMW119-attR-cat- attL-P 14 -acnA-P 14 -aldB stock.

[Example 5] Evaluation of L-lysine-producing ability of L-lysine-producing bacteria Each glycerol stock obtained in Example 2, Example 3, and Example 4 was thawed, and about 100 μL was added to 100 mg / L of ampicillin. The solution was uniformly applied to an L plate containing and cultured at 37 ° C. for 16 hours. After static culture, the obtained cells are suspended in 0.85% saline and contain 100 mg / L ampicillin placed in a 500 mL Sakaguchi flask so that the turbidity (OD600) at a wavelength of 600 nm is 0.2. 25 mL of fermentation medium (below) was inoculated and cultured at 37 ° C. for 24 hours under the condition of stirring at 120 rpm in a reciprocating shake culture apparatus. After 24 hours of shaking culture, 125 μL of ethanol was added to each flask, and further cultured under shaking under the same conditions for 17 hours.

The composition of the fermentation medium is shown below.
Ethanol 10 ml / L
(NH ₄ ) ₂ SO ₄ 24 g / L
KH ₂ PO ₄ 1.0 g / L
MgSO ₄・ 7H ₂ O 1.0 g / L
FeSO ₄・ 7H ₂ O 0.01 g / L
MnSO ₄・ 5H ₂ O 0.082 g / L
Yeast Extract (Difco) 2.0 g / L
CaCO ₃ (Japanese Pharmacopoeia) 40 g / L
Distilled water Final volume 1 L

After completion of the culture, the amount of L-lysine accumulated in the medium was measured using Biotech Analyzer AS310 (manufactured by Sakura Seiki Co., Ltd.). In addition, it was confirmed by ethanol using Biotech Analyzer BF-5 (Oji Scientific Instruments) that all the carbon sources added to the medium were consumed. Furthermore, immediately after completion of the culture, the culture solution is appropriately diluted with 0.2N dilute hydrochloric acid, and the turbidity (OD ₆₀₀ ) at a wavelength of 600 nm is measured with a spectrophotometer U-2000 (manufactured by Hitachi), so that the cells at the end of the culture are obtained. The amount was measured.

The results are shown in Table 1. In Table 1, “Strain” indicates the name of the strain. In Table 1, “Lys (g / L)” indicates the amount of L-lysine accumulated in the medium. enhanced expression strain acnB gene (AJIK01m2 / pMW119-attR-cat -attL-P 14 -acnB strain), compared to the control strain (AJIK01m2 / pMW119-attR-cat -attL-P 14 strain), significantly higher L-lysine production was shown. That is, it was shown that the L-lysine production ability is improved by enhancing the expression of the acnB gene. Further, acnB and enhanced expression strain (AJIK01m2 / pMW119-attR-cat -attL-P 14 -acnB-P 14 -aldB strain) of both genes of aldB is control strain (AJIK01m2 / pMW119-attR-cat -attL-P Compared with ₁₄ strains), it showed significantly higher L-lysine production. That is, it was shown that L-lysine production ability was improved by enhancing the simultaneous expression of acnB gene and aldB gene. Further, acnA and enhanced expression strain (AJIK01m2 / pMW119-attR-cat -attL-P 14 -acnA-P 14 -aldB strain) of both genes of aldB is control strain (AJIK01m2 / pMW119-attR-cat -attL-P Compared with ₁₄ strains), it showed significantly higher L-lysine production. That is, it was shown that the L-lysine production ability was improved by enhancing the simultaneous expression of the acnA gene and the aldb gene.

According to the present invention, the ability of bacteria to produce L-amino acids can be improved, and L-amino acids can be produced efficiently.

<Explanation of Sequence Listing>
SEQ ID NO: 1: nucleotide sequence of promoter P ₁₄ SEQ ID NO: 2 to 20: primer SEQ ID NO: 21: nucleotide sequence of acnA gene of Escherichia coli K12 MG1655 strain SEQ ID NO: 22: amino acid sequence of AcnA protein of Escherichia coli K12 MG1655 strain SEQ ID NO: 23 : Nucleotide sequence of the acnA gene of Pantoea ananatis AJ13355 strain SEQ ID NO: 24: amino acid sequence of the AcnA protein of Pantoea ananatis AJ13355 sequence SEQ ID NO: 25: nucleotide sequence of the acnA gene of Pectobacterium atrosepticum SCRI1043 strain: AcnA protein of the Pectobacterium atrosepticum SCRI1043 strain SEQ ID NO: 27: nucleotide sequence of acnA gene of Salmonella enterica serovar Typhi CT18 strain SEQ ID NO: 28: amino acid sequence of AcnA protein of Salmonella enterica serovar Typhi CT18 strain SEQ ID NO: 29: nucleotide sequence of acnB gene of Escherichia coli K12 MG1655 strain SEQ ID NO: 30: AcnB protein amino acid of Escherichia coli K12 MG1655 strain Acid sequence SEQ ID NO: 31: nucleotide sequence of the acnB gene of Pantoea ananatis AJ13355 strain SEQ ID NO: 32: amino acid sequence of the AcnB protein of Pantoea ananatis AJ13355 strain SEQ ID NO: 33: nucleotide sequence of the acnB gene of Pectobacterium atrosepticum SCRI1043 strain SEQ ID NO: 34: Pectobacterium atrosepticum The amino acid sequence of the AcnB protein of SCRI1043 strain SEQ ID NO: 35: The nucleotide sequence of the acnB gene of Salmonella enterica serovar Typhi CT18 strain SEQ ID NO: 36: The amino acid sequence of the AcnB protein of Salmonella enterica serovar Typhi CT18 strain SEQ ID NO: 37: Escherichia coli K12 MG1655 strain Base sequence of aldB gene SEQ ID NO: 38: Amino acid sequence of AldB protein of Escherichia coli K12 MG1655 strain SEQ ID NO: 39: Base sequence of aldB gene of Pantoea ananatis LMG 20103 strain SEQ ID NO: 40: Amino acid sequence of AldB protein of Pantoea ananatis LMG 20103 strain SEQ ID NO: 41: aldb gene of Pectobacterium atrosepticum SCRI1043 strain Base sequence SEQ ID NO: 42: amino acid sequence of AldB protein of Pectobacterium atrosepticum SCRI1043 strain SEQ ID NO: 43: Base sequence sequence number of aldB gene of Salmonella enterica serovar Typhi CT18 strain 44: Amino acid sequence sequence number of AldB protein of Salmonella enterica serovar Typhi CT18 strain 45: base sequence of the adhE gene of Escherichia coli K12 MG1655 strain SEQ ID NO: 46: amino acid sequence of the AdhE protein of Escherichia coli K12 MG1655 strain SEQ ID NO: 47: base sequence of the adhE gene of Pantoea ananatis LMG 20103 strain SEQ ID NO: 48: Pantoea ananatis LMG AdhE protein of the 20103 strain SEQ ID NO: 49: nucleotide sequence of the adhE gene of the Pectobacterium atrosepticum SCRI1043 strain SEQ ID NO: 50: amino acid sequence of the AdhE protein of the Pectobacterium atrosepticum SCRI1043 strain SEQ ID NO: 51: adhE gene of the Salmonella enterica serovar Typhi CT18 strain Base sequence SEQ ID NO: 52: Salmonella enterica serovar Amino acid sequence of AdhE protein of Typhi CT18 strain

Claims

Bacteria belonging to the family Enterobacteriaceae having L-amino acid producing ability are cultured in a medium containing ethanol, and L-amino acid is produced and accumulated in the medium or in the microbial cells, and from the medium or the microbial cells Collecting the L-amino acid, comprising the steps of:
The bacterium is modified to increase aconitase activity,
The method wherein the aconitase is an AcnB protein.
The method according to claim 1, wherein the AcnB protein is a protein described in the following (a), (b), or (c):
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36;
(B) In the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36, the amino acid sequence includes substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and has an aconitase activity. protein;
(C) a protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36 and having aconitase activity.
Bacteria belonging to the family Enterobacteriaceae having L-amino acid producing ability are cultured in a medium containing ethanol, and L-amino acid is produced and accumulated in the medium or in the microbial cells, and from the medium or the microbial cells Collecting the L-amino acid, comprising the steps of:
A method wherein the bacterium has been modified to increase aconitase activity and acetaldehyde dehydrogenase activity.
The method according to claim 3, wherein the aconitase is an AcnA protein or an AcnB protein.
The method according to claim 4, wherein the AcnA protein is a protein described in the following (a), (b), or (c):
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 22, 24, 26, or 28;
(B) In the amino acid sequence shown in SEQ ID NO: 22, 24, 26, or 28, includes an amino acid sequence including substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and has an aconitase activity. protein;
(C) a protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 22, 24, 26, or 28 and having aconitase activity.
The method according to claim 4, wherein the AcnB protein is a protein described in (a), (b), or (c) below:
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36;
(B) In the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36, the amino acid sequence includes substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and has an aconitase activity. protein;
(C) a protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 30, 32, 34, or 36 and having aconitase activity.
The method according to any one of claims 3 to 6, wherein the acetaldehyde dehydrogenase is an AldB protein.
The method according to claim 7, wherein the AldB protein is a protein described in the following (a), (b), or (c):
(A) a protein comprising the amino acid sequence shown in SEQ ID NO: 38, 40, 42, or 44;
(B) the amino acid sequence shown in SEQ ID NO: 38, 40, 42, or 44, comprising an amino acid sequence comprising substitution, deletion, insertion, or addition of 1 to 10 amino acid residues, and having acetaldehyde dehydrogenase activity A protein having;
(C) A protein comprising an amino acid sequence having 90% or more identity to the amino acid sequence shown in SEQ ID NO: 38, 40, 42, or 44 and having acetaldehyde dehydrogenase activity.
The method according to any one of claims 1 to 8, wherein the bacterium is further modified to increase the activity of an ethanol metabolizing enzyme.
The method according to any one of claims 1 to 9, wherein the bacterium can assimilate ethanol aerobically.
The bacterium has been modified to retain a mutant adhE gene;
The method according to any one of claims 1 to 10, wherein the mutant adhE gene is an adhE gene encoding a mutant AdhE protein having a mutation that improves resistance to inactivation under aerobic conditions.
The mutation is a mutation in which the amino acid residue corresponding to the glutamic acid residue at position 568 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with an amino acid residue other than glutamic acid and aspartic acid in the amino acid sequence of the wild-type AdhE protein. The method of claim 11, wherein:
The method according to claim 12, wherein the amino acid residue after substitution is a lysine residue.
The method according to claim 12 or 13, wherein the mutant AdhE protein further has the following additional mutation. :
(A) A mutation in which the amino acid residue corresponding to the glutamic acid residue at position 560 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with another amino acid residue in the amino acid sequence of the wild-type AdhE protein;
(B) a mutation in which the amino acid residue corresponding to the phenylalanine residue at position 566 in the amino acid sequence shown in SEQ ID NO: 46 is substituted with another amino acid residue in the amino acid sequence of the wild-type AdhE protein;
(C) In the amino acid sequence of the wild-type AdhE protein, the glutamic acid residue at position 22, the methionine residue at position 236, the tyrosine residue at position 461, the isoleucine residue at position 554, and 786 in the amino acid sequence shown in SEQ ID NO: 46 A mutation in which the amino acid residue corresponding to the alanine residue at the position is substituted with another amino acid residue;
(D) Combination of the above mutations.
The method according to any one of claims 1 to 14, wherein the bacterium is an Escherichia bacterium.
The method according to claim 15, wherein the bacterium is Escherichia coli.
The method according to any one of claims 1 to 16, wherein the L-amino acid is L-lysine.
18. The method of claim 17, wherein the bacterium further has the following properties:
(A) Dihydrodipicolinate reductase, diaminopimelate decarboxylase, diaminopimelate dehydrogenase, phosphoenolpyruvate carboxylase, aspartate aminotransferase, diaminopimelate epimerase, aspartate semialdehyde dehydrogenase, tetrahydrodipicolinate succinylase, and succinyl diaminopimelate deacylase Modified to increase the activity of one or more enzymes selected from
(B) modified to reduce the activity of lysine decarboxylase;
(C) A combination of the above properties.